Chapter 7Introduction to Probability 1

Chapter 7Introduction to Probability 1

Warm-up Exercise(page 7.1)

1.(a)Fraction required

(b)Fraction required

(c)Fraction required

2.(a)Area

(corr. to 3 sig. fig.)

(b)Area

(corr. to 3 sig. fig.)

(c)Area

(corr. to 3 sig. fig.)

3.(a)Area

(b)Area

(c)Area

Build-up Exercise

Exercise 7A

Elementary Set(page 7.2)

1.P(Herbert)

2.P(Mr. Wong)

3.(a)P(letter ‘M’)

(b)P(letter ‘E’)

4.P(February, April, June, August, October or

December)

5.P(black goldfish from fishpond A)

P(black goldfish from fishpond B)

Fishpond A has a higher probability of

getting a black goldfish.

6.P(tourist from Beijing)

Number of tourists from Beijing /
Total number of tourists

Number of tourists from Beijing

Total number of tourists

41 tourists from Beijing have entered

OceanPark over the past hour.

7.P(student with glasses)

Number of students with glasses /
Total number of students

Total number of students

Number of students with glasses

There are 39 students in S3A.

8.(a)P(information technology department or

personnel department)

(b)Number of staff members from warehouse department joining the Christmasparty

P(neither personnel department nor

warehouse department)

9.(a)P(Chinese and English newspapers)

(b)P(subscribe one newspaper only)

10.According to the figure, 92 students score 80 marks below.

P(grade A)

11.Let the number of toy trains made by machine B be y.

P(machine A)

The number of toy trains made by

machine B is.

12.Let x be the number of tickets with prizes of a doll each that should be added.

P(doll)

5 tickets with prizes of a doll each

should be added.

13.Let the number of cartons of lemon tea on the table be x, then there are (x5)cartons of apple juice on the table.

P(lemon tea)

There are 20 cartons of lemon tea on the

table originally.

14.Let the number of red ball pens be x, then the number of blue ball pens is x3.

P(red ball pen)0.4

Total number of ball pens in the box

Advanced Set(page 7.4)

1.P(under 16)

2.P(Rachel)

3.P(‘J’)

4.P(16 or above)

5.P(flat occupied by less than four family

members)

6.P(girl from Mathematics club)

P(girl from Physics club)

Mathematics club has a higher

probability of selecting a girl.

7.P(American)

Number of American /
Total number of passengers

Number of American

Total number of passengers

There are 24 American passengers in the

aeroplane.

8.P(orange flavour)

Number of packs oforange flavour candies /
Number of packs of all candies

Number of packs of all candies

Number of packs of orange

flavour candies

There are 24 packs of candies in the box.

9.(a)P(learning both piano and violin)

(b)P(learning only one kind of musical

instrument)

10.(a)P(Computer club or Mathematics club)

(b)P(Neither Computer club nor Sport club)

11.According to the figure, 36 students score below 50 marks.

P(pass)

12.(a)Let the number of bulbs produced by production line B bey.

P(production line A)

x /
Total number of bulbs

Total number of bulbs

P(production line B)

y /
Total number of bulbs

Total number of bulbs

The number of bulbs produced by

production line B is.

(b)P(production line A)

The number of bulbs produced by

production line A is 1000.

13.Let the original number of lottery tickets be x,then the present number of lottery tickets is x+240.

Number of lottery tickets with a prize /
Original number of lottery tickets

Number of lottery tickets with a prize

Original number of lottery tickets

Number of lottery tickets with a prize /
Present number oflottery tickets

The original number of lottery tickets

is 120.

14.Let the number of VCDs bex, then the number of DVDs isx10 and thenumber of CDs is x4.

P(VCD)

The number of VCDs on the shelf is 20.

15.(a)P(chocolate cake)

(b)P(chocolate cake)

(c)P(mango cake)

Exercise 7B

Elementary Set(page 7.7)

1.Relative frequency of the number of days for Philip being late for school

2.(a)Experimental probability of getting a packet with 42 chocolates

(b)Experimental probability of getting a standard packet

3.(a)Total frequency

Relative frequency of not travelling by bus in one day

(b)Relative frequency of travelling by bus in one day

4.(a)Total number of students

Relative frequency with IQ lies between96 and 105 inclusive

(b)Relative frequency with IQ higher than 105

5.(a) /  / Number of rotten eggs chosen
Number of eggs chosen

Relative frequency of rotten eggs



(b)Number of rotten eggs expected

The number of rotten eggs expected

is 200.

6.Yes, because when the number of experiments done increases, the experimental probability for the coin to toss a ‘head’ becomes nearer to the theoretical probability for a fair coin to toss a ‘head’.

7.(a)(i)Experimental probability that the weight of a moon cake lies between 221g and 230g inclusive

(ii)Experimental probability that the weight of a moon cake lies between 241g and 250g inclusive

(iii)Experimental probability that the weight of a moon cake is more than 230.5g

(b)Estimated number of moon cakes which weigh more than 230.5g

8.(a)(i)Experimental probability that the person watches the news channel most frequently

(ii)Experimental probability that the person watches the drama channel or entertainment channel most frequently

(b)I will choose the entertainment channel because it seems that people watch the entertainment channel most frequently in the evening.

(c)Estimated number of people who watch the news channel most frequently

Advanced Set(page 7.9)

1.(a)Total number of the group of Japanese tourists

Relative frequency that it is the tourist’s first time visitingHong Kong

(b)Relative frequency that it is the tourist’s fourth time visitingHong Kong

2.(a)Relative frequency for Derek to sleep less than 8 hours at night

(b)Relative frequency for Derek to sleep at least 7 hours but less than 9 hours

3.(a)Total number of students

Experimental probability that the height of a S3 student lies between 140cm and 169cm inclusive

(b)Experimental probability that the height of a S3 student is less than 140cm

4.(a)Relative frequency of defective electronic components

 / Number of defectivecomponents /
Number of components chosen

(b)Estimated number of defective electronic components

The estimated number of defective

electronic components is 32.

5.(a)Relative frequency of misprinted copies



(b)Estimated number of misprinted copies

The estimated number of misprinted

copies is 48.

6.They are different because the numbers of red balls and black balls drawn in the three experiments of drawing 100 balls, 1000 balls and 10000 balls all differ from each other a lot.

7.(a)Relative frequency of the crows in the district with the rings

(b)Relative frequency of the crows with the rings

 / Total number of crows
with the rings /
Estimated total number
of crows

Estimated total number of crows

Total number of crows with the

rings

The estimated number of crows in

the district is 1250.

8.(a)P(Orange Daily)

(b)P(Southern Daily, age30)

(c)P(age30)

(d)From the result of the survey, Chiu Daily is the most frequently read newspaper with people of age 30 or below, and the cost of posting advertisement on Chiu Daily is reasonable. Thus the company should choose Chiu Daily for posting the advertisement.

Exercise 7C

Elementary Set(page 7.11)

1.(a)H, T

(b)HH, HT, TH, TT

2.The possible combinations are as follows.

Chinese History and Computer Studies,

Chinese History and Geography,

Chinese History and Economics,

History and Computer Studies,

History and Geography,

History and Economics

There are 6 possible combinations.

3.(a)

(b)P(WW)

4.(a)

(b)8 possible outcomes are obtained in (a).

(c)P(2 sons and 1 daughter)

5. / 2nd dice
1 / 2 / 3 / 4 / 5 / 6
1st dice / 1 / (1,1) / (1,2) / (1,3) / (1,4) / (1,5) / (1,6)
2 / (2,1) / (2,2) / (2,3) / (2,4) / (2,5) / (2,6)
3 / (3,1) / (3,2) / (3,3) / (3,4) / (3,5) / (3,6)
4 / (4,1) / (4,2) / (4,3) / (4,4) / (4,5) / (4,6)
5 / (5,1) / (5,2) / (5,3) / (5,4) / (5,5) / (5,6)
6 / (6,1) / (6,2) / (6,3) / (6,4) / (6,5) / (6,6)

(a)All possible outcomes of

‘the difference is 3’ are as follows.

(1,4), (2,5), (3,6), (4,1), (5,2), (6,3)

Probability required

(b)All possible outcomes of

‘the product is less than 10’ are as follows.

(1,1),(1,2),(1,3),(1,4),(1,5),(1,6),(2,1),(2,2),(2,3),(2,4),(3,1),(3,2),(3,3),(4,1),(4,2),(5,1),(6,1)

Probability required

6. / (a) / O / R / A / N / G / E
A / AO / AR / AA / AN / AG / AE
P / PO / PR / PA / PN / PG / PE
P / PO / PR / PA / PN / PG / PE
L / LO / LR / LA / LN / LG / LE
E / EO / ER / EA / EN / EG / EE

(b)(i)P(two letters are the same)

(ii)P(two letters are vowels)

7. / BoxA
BoxB / $10 / $20 / $50 / $100 / $500 / $1000
0 / $0 / $0 / $0 / $0 / $0 / $0
0.5 / $5 / $10 / $25 / $50 / $250 / $500
1 / $10 / $20 / $50 / $100 / $500 / $1000
5 / $50 / $100 / $250 / $500 / $2500 / $5000
10 / $100 / $200 / $500 / $1000 / $5000 / $10000

(a)P(cash prize of $0)

(b)P(cash prize of $100)

(c)P(cash prize over $500)

8. / (a) / 2ndcard
1stcard / F / O / U / R
F / FO / FU / FR
O / OF / OU / OR
U / UF / UO / UR
R / RF / RO / RU

(b)(i)P(two cards are the same)

(ii)P(two cards can form ‘OR’)

9. / 2nd banknote ($)
20 / 20 / 20 / 50 / 50 / 100
1st banknote ($) / 20 / (20,20) / (20,20) / (20,50) / (20,50) / (20,100)
20 / (20,20) / (20,20) / (20,50) / (20,50) / (20,100)
20 / (20,20) / (20,20) / (20,50) / (20,50) / (20,100)
50 / (50,20) / (50,20) / (50,20) / (50,50) / (50,100)
50 / (50,20) / (50,20) / (50,20) / (50,50) / (50,100)
100 / (100,20) / (100,20) / (100,20) / (100,50) / (100,50)

(a)P(two banknotes with equal face value)

(b)P(two banknotes with different face

values)

10.(a)

(b)(i)Number of outcomes of getting two customers who buy drink most frequently

(ii)Total number of possible outcomes of getting two customers

(c)P(two customers buying drink most

frequently)

Advanced Set(page 7.14)

1.Let R1 and R2denote the 2 red scarves, and W1, W2andW3denote the 3 white scarves.

2nd scarf
1st scarf / R1 / R2 / W1 / W2 / W3
R1 / R1R1 / R1R2 / R1W1 / R1W2 / R1W3
R2 / R2R1 / R2R2 / R2W1 / R2W2 / R2W3
W1 / W1R1 / W1R2 / W1W1 / W1W2 / W1W3
W2 / W2R1 / W2R2 / W2W1 / W2W2 / W2W3
W3 / W3R1 / W3R2 / W3W1 / W3W2 / W3W3

(a)P(same scarf)

(b)P(scarves in the same colour)

2.(a)222, 223, 232, 233, 322, 323, 332, 333

(b)(i)P(only one digit is ‘2’)

(ii)P(even number)

3. / 2nd dice
1 / 2 / 3 / 4 / 5 / 6
1st dice / 1 / (1,1) / (1,2) / (1,3) / (1,4) / (1,5) / (1,6)
2 / (2,1) / (2,2) / (2,3) / (2,4) / (2,5) / (2,6)
3 / (3,1) / (3,2) / (3,3) / (3,4) / (3,5) / (3,6)
4 / (4,1) / (4,2) / (4,3) / (4,4) / (4,5) / (4,6)
5 / (5,1) / (5,2) / (5,3) / (5,4) / (5,5) / (5,6)
6 / (6,1) / (6,2) / (6,3) / (6,4) / (6,5) / (6,6)

All possible outcomes of event A are as follows.

(1,2), (2,1),(2,3),(3,2),(3,4),(4,3),

(4,5),(5,4),(5,6),(6,5)

All possible outcomes of event B are as follows.

(1,1),(2,2),(3,3),(4,4),(5,5),(6,6)

Event A is more likely to occur.

4. / (a) / D / I / S / A / B / L / E
A / AD / AI / AS / AA / AB / AL / AE
B / BD / BI / BS / BA / BB / BL / BE
I / ID / II / IS / IA / IB / IL / IE
L / LD / LI / LS / LA / LB / LL / LE
I / ID / II / IS / IA / IB / IL / IE
T / TD / TI / TS / TA / TB / TL / TE
Y / YD / YI / YS / YA / YB / YL / YE

(b)(i)P(two letters are the same)

(ii)P(two letters are consonants)

5. / (a) / 2nd ball
R1 / R2 / B1 / B2 / W1 / W2 / W3
1st ball / R1 / R1R2 / R1B1 / R1B2 / R1W1 / R1W2 / R1W3
R2 / R2R1 / R2B1 / R2B2 / R2W1 / R2W2 / R2W3
B1 / B1R1 / B1R2 / B1B2 / B1W1 / B1W2 / B1W3
B2 / B2R1 / B2R2 / B2B1 / B2W1 / B2W2 / B2W3
W1 / W1R1 / W1R2 / W1B1 / W1B2 / W1W2 / W1W3
W2 / W2R1 / W2R2 / W2B1 / W2B2 / W2W1 / W2W3
W3 / W3R1 / W3R2 / W3B1 / W3B2 / W3W1 / W3W2

(b)(i)P(two black balls)

(ii)P(two white balls)

(iii)P(two balls of the same colour)

(iv)P(one black ball and one white ball)

6. / 1 / 3 / 5 / 7
1 / (1,3) / (1,5) / (1,7)
3 / (3,1) / (3,5) / (3,7)
5 / (5,1) / (5,3) / (5,7)
7 / (7,1) / (7,3) / (7,5)

The possible outcomes of ‘a sum of 8’are as follows.

(1,7),(3,5),(5,3), (7,1)

Probability required

7.Let D denote doll, C denote chocolate, P denote colour pencil and S denote storybook.

2nd prize
D / C / C / P / P
1st prize / D / DC / DC / DP / DP
C / CD / CC / CP / CP
C / CD / CC / CP / CP
P / PD / PC / PC / PP
P / PD / PC / PC / PP
P / PD / PC / PC / PP / PP
S / SD / SC / SC / SP / SP
S / SD / SC / SC / SP / SP
S / SD / SC / SC / SP / SP
S / SD / SC / SC / SP / SP
2nd prize
P / S / S / S / S
1st prize / D / DP / DS / DS / DS / DS
C / CP / CS / CS / CS / CS
C / CP / CS / CS / CS / CS
P / PP / PS / PS / PS / PS
P / PP / PS / PS / PS / PS
P / PS / PS / PS / PS
S / SP / SS / SS / SS
S / SP / SS / SS / SS
S / SP / SS / SS / SS
S / SP / SS / SS / SS

P(not getting a storybook)

P(getting a storybook)

P(getting a storybook)

P(not getting a storybook)

The probability of getting a storybook

ishigher than that of not getting a

storybook.

8.(a)

(b)(i)Number of possible outcomes of getting two people who vote for Jenny

(ii)Total number of possible outcomes of getting two people

(c)P(getting two people vote for Jenny)

9.Let R denote red ball and W denote white ball.

2nd ball
1st ball / R / W / W / Balls added afterwards
R / W
R / RW / RW / RR / RW
W / WR / WW / WR / WW
W / WR / WW / WR / WW

(a)P(two balls in different colours)

(b)P(getting white ball first, then getting

red ball)

Exercise 7D

Elementary Set(page 7.16)

1. / Probability that the point locates in region I
 / Area of region I
Area of the square card

2.

Area of the square2Area of ABC

Area of the circle

 / Probability of hitting on the square region
 / Area of square
Area of circle

3.(a)Area of the dartboard

 / Probability of hitting on circle A
 / Area of circle A
Area of the dartboard
(b) / Probability of hitting on a circle
 / Area of four circles
Area of the dartboard
4. / Probability of not stopping withinthe circular region
 / Area of the white region
Area of the square

5.(a)Expected value of the scores obtained by the team in each match

(b)Estimated total score of the team

6.(a)Area of the shaded region

Area of the dartboard

Probability of hitting the shaded region

 / Area of the shaded region
Area of the dartboard

(b)Area of the white region

Probability of getting 2 marks

Probability of hitting the white region

 / Area of the white region
Area of the dartboard

(c)Expected value of each throw

7.(a)Probability of winning 1st prize

(b)Probability of winning a prize

(c)Expected value of Stanley’s lucky draw ticket

8.Expected value of the score of each question

Expected value of his score0





9.(a)Expected value of the travelling time to work of Mr. Cheung

minutes

minutes

(b)Expected value of the fare to work of Mr. Cheung

10.All the possible outcomes each round are as follows.

HH, HT, TH, TT

Expected value of the result obtained after each round

0

Expected value of the result obtained after ten rounds

0

Advanced Set(page 7.18)

1.Probability that the point is marked on the shaded region

 / Area of the shaded region
Area of the paper

2.Let the diameter of the circular dartboard be dcm.

According to the Pythagoras’ theorem,

Area of the dartboard

Area of the shaded region

Probability of hitting on the shaded region

 / Area of the shaded region
Area of the dartboard

3.(a)Area of figure I

Area of figure II2Area of figure I

Area of figure III

Area of figure IV

Area of the picture

Probability that the bug rests on either figure II or IV

 / Area of figure IIArea of figure IV
Area of the picture

(b)Sum of the areas of the 4 figures

Probability that the bug rests on neither figure I, II, III nor IV

 / Area of the picture
Sum of the areas of the 4 figures
Area of the picture

4.Number of banknotes in the wallet

Expected value of the amount of the banknote

5.(a)Probability of hitting region I

 / Area of region I
Area of the dartboard

Probability of hitting region II

Probability of hitting region I

Probability of hitting region III

 / Area of region III
Area of the dartboard

Probability of hitting region IV

Probability of hitting region III

(b)Expected value of the points scored

6.(a)Expected value of the amount spent by Denise on breakfast each day

(b)Expected value of the time spent by Denise on breakfast each day

minutes

minutes

7.Let R denote red ball and W denote white ball.

2nd ball
1st ball / R / W / W / W
R / RR / RW / RW / RW
W / WR / WW / WW / WW
W / WR / WW / WW / WW
W / WR / WW / WW / WW

(a)Probability of getting two red balls

(b)Probability of getting two ballsin different colours

(c)Probability of getting two white balls

(d)Expected value of the cash prize obtained

(e)No, because the fee for joining the lucky draw is greater than the expected value of the cash prize obtained.

8.(a) / Probability of hitting region I
 / Area of region I
Area of the dartboard
Probability of hitting region II
 / Area of region II
Area of the dartboard
Probability of hitting region III
 / Area of region III
Area of the dartboard

Expected value of the points scored0



(b)According to the result in part (a),

Since zis an integer greater than 12, the least value of z is 13.

When z13,

10,

which is an integer smaller than 12

x10 and z13 are one set of possible integral values of x and z.

When z14,

,

which is a number greater than 12

z14 is not a possible integral value of z.

For,where 0x12z, the value of x increases as the value of zincreases, i.e. when the value of z is greater,the value of x is also greater. Thus when z is an integer greater than 14, the value of x is greater than,i.e. greater than 12.

x10 and z13 is the only set of

possible integral values of x and z.

9.(a)

(b)Probability that a train stays in the station when Raymond arrives

Chapter Test (page 7.20)

1.P(red)

2. / 2nd child
1st child / Boy / Girl
Boy / Boy Boy / Boy Girl
Girl / Girl Boy / Girl Girl

Probability that both are boys

3.There are 21 integers from 20 to 40inclusive. Within which all integers not divisible by 4 are as follows.

21, 22, 23, 25, 26, 27, 29, 30, 31, 33, 34, 35, 37, 38, 39

P(not divisible by 4)

4.Probability of hitting on region A

5.Probability of getting a rotten orange

6.Probability that the student passed the test

7. / S / A / D
H / HS / HA / HD
A / AS / AA / AD
P / PS / PA / PD
P / PS / PA / PD
Y / YS / YA / YD

Probability of getting at least one ‘A’

8.(a)Total number of drink in the refrigerator

Probability of choosing a can of orange juice

(b)Expected value of the price of the drink

9.(a)Probability that the vote is for singer C

(b)Estimated total number of votes for singer C

10.(a) / Probability of hitting on the 3-point region
 / Area of the 3-point region
Area of the dartboard
(b) / Probability of hitting on the 2-point region
 / Area of the 2-point region
Area of the dartboard

11.(a)Number of students who are members of both clubs

8 students are members of both clubs.

(b)Probability that the student is not a member of Mathematics club

(c)Probability that the student is a member of either one of the clubs

12.Obtaining two heads is a possible outcome of tossing a coin twice.

I is not an impossible event.

Obtaining a white sock and a blue sock is a possible outcome of drawing two socks from 3 pairs of socks in blue, white and black each.

II is not an impossible event.

The sum of numbers obtained by tossing two dice is at most 12.

III is an impossible event.

The answer is B.

13.For any event E,.

I is correct.

Experimental probability of an event
 / Number of trials favourable to the event
Total number of trials

II is correct.

P(E)

 / Number of outcomes favourable to event E
Total number of possible outcomes

III is not correct.

The answer is C.

14.Let M denote male and F denote female.

M / M / M / M / F / F
M / M M / M M / M M / M F / M F
M / M M / M M / M M / M F / M F
M / M M / M M / M M / M F / M F
M / M M / M M / M M / M F / M F
F / F M / F M / F M / F M / F F
F / F M / F M / F M / F M / F F

P(one male one female)

The answer is D.

15. / 2nd card
1st card / ) / 2 / 3 / 4 / 5
2 / 6 / 8 / 10
3 / 6 / 12 / 15
4 / 8 / 12 / 20
5 / 10 / 15 / 20

P(product of the two numbers is an even

number)

P(product of the two numbers is a prime

number)

2nd card
2 / 3 / 4 / 5
1st card / 2 / (2,3) / (2,4) / (2,5)
3 / (3,2) / (3,4) / (3,5)
4 / (4,2) / (4,3) / (4,5)
5 / (5,2) / (5,3) / (5,4)

P(two numbers are even numbers)

P(two numbers are prime numbers)

‘The product of two numbers is an even number’ will happen with the highest probability.

The answer is A.

16.Expected value of buying an item by Adams

The answer is C.

17.Expected value of the return after 6 months

The answer is D.

18. / 2nd question
1st question / Correct / Wrong
Correct / 2 / 0
Wrong / 0 / 2

Probability of obtaining 1 mark or above

The answer is C.

19.Let the number of white balls in the bag be n.

P(white ball)0.4

Number of white balls in the bag12

The answer is C.

20.Probability that the student is wearing glasses

The answer is D.

21. / 2nd dice
1st dice / ) / 1 / 2 / 3 / 4 / 5 / 6
1 / 2 / 3 / 4 / 5 / 6 / 7
2 / 3 / 4 / 5 / 6 / 7 / 8
3 / 4 / 5 / 6 / 7 / 8 / 9
4 / 5 / 6 / 7 / 8 / 9 / 10
5 / 6 / 7 / 8 / 9 / 10 / 11
6 / 7 / 8 / 9 / 10 / 11 / 12

P(sum of numbers10)

The answer is C.

22.There are 100 integers from 1 to 100 inclusive within which all the integers divisible by 5 are as follows.

5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100

P(divisible by 5)

The answer is B.

23.

P(distance between the point and centre not more than 1cm)

 / Area of the circle with radius 1cm
Area of the circle with radius 2cm

The answer is A.

24.P(black ball)

P(white ball)

P(black ball)P(white ball)

Total number of balls in the bag

The answer is A.

25.Let R denote red ball and B denote blue ball.

2nd ball
1st ball / R / B / B / B
R / RB / RB / RB
B / BR / BB / BB
B / BR / BB / BB
B / BR / BB / BB

Probability that the 2nd ball drawn is red in colour

The answer is C.

26.Number of male ex-classmates of Kiki

Number of female ex-classmates of Kiki

Probability that she talks with her ex-classmate

The answer is A.

Open-ended questions have been broadly advocated for education in Hong Kong secondary schools following the current curriculum reform. In view of this, new strategies are required not only for teaching mathematics but also for assessing student’s performance.At this transitional stage, we have introduced in the ‘Open-ended Question Zone’ of New Trend Mathematics – Junior Form SupplementaryExercisesa simple assessment scheme for open-ended questions. At the same time, a more detailed assessment scheme is also provided in the article ‘Ideas for Mathematics Teaching’ in our New Trend Mathematics S1 to S3 Teacher’s CD. Teachers may refer to these two assessment schemes, or others which they may come across, and choose to adopt an appropriate one according to their need.

Exercise of Open-ended Questions 7

(page 7.28)

1.If the number of vowels is greater than the number of consonants in a word, then the probability of choosing a vowel from this word is greater than that of choosing a consonant.

‘You’ and ‘about’ are two required words.

Scoring:2 marks for correct answer;

2 marks for clear explanation.