PRACTICE TEST #3 (SOLUTIONS)

20. A)

B) linear, negative, fairly strong

.

C) =

D) =

=

or Plugging in x = 100 we get y = 27.19 and plugging in x = 250 we get y = 15.82. Next we plot the points and draw the line in the graph above.

E) 15.82 MPG (work in part D)

F) Good or bad is an OK answer, if the reasons are right:

GOOD: high correlation, 250 is near middle of the data are reasons

BAD: somewhat small sample size, correlation could be higher

From looking at the graph it looks like the prediction should be within +/- 5 or 10 MPG

G) For every additional HP the best guess is that the MPG goes down by .0758. Or for every additional 100 HP the MPG goes down by 7.58.

H)

23. A) White murderers: 23/153 = 15.03% got death penalty

Black murderers: 12/62 = 19.35% got death penalty

Blacks had a higher chance of getting death penalty.

B) White murderers: 1/12 = 8.33% got death penalty

Black murderers: 10/107 = 9.35% got death penalty

Blacks had a higher chance of getting death penalty.

C) White murderers: 24/165 = 14.55% got death penalty

Black murderers: 22/169 = 13.02% got death penalty

Whites had a higher chance of getting death penalty.

24.

Student Meetings / Faculty Meetings
Sugar / 50 / 20
Chocolate Chip / 102 / 55
Oatmeal / 66 / 42
Peanut Butter / 44 / 18
Totals / 262 / 135
Student Meetings / Faculty Meetings
Sugar / 50/262 = 19.1% / 20/135 = 14.8%
Chocolate Chip / 102/262 = 38.9% / 55/135 = 40.7%
Oatmeal / 66/262 = 25.2% / 42/135 = 31.1%
Peanut Butter / 44/262 = 16.8% / 18/135 = 13.3%

75.

percents not as in

Visa / MC / AE / Other
O / 140 / 96 / 24 / 40 / 300
E / (300)(50%) = 150 / (300)(30%) = 90 / (300)(10%)=30 / 30 / 300

df = 4 – 1 = 3

Picture of how ’s would be distributed if the percentage were as claimed in . The best evidence is in the right tail with area 10%.

NO

76. . same percent for each category, namely

percents not as in

each

O’s / Red / Green / Silver
Almonds / 45 / 51 / 48
Peanuts / 55 / 50 / 48
No Nuts / 60 / 47 / 46

df = 9 – 1 = 8

Picture of how ’s would be distributed if the percentages were all the same. The best evidence is in the right tail with area 5%.

NO

77. 3.68 falls between 3.490 and 13.362 on the table with df = 8. So the p-value is between 10% and 90% (much closer to 90%).

If the percents are equal, the chance we would get evidence as strong as or stronger than we got that they differ is between 10% and 90%. This is assuming all conditions were met and the data were gathered properly.

78. wrapping color and nuts independent

some relationship between wrapping color and nuts

df = (3-1)(3-1) = 4

O’s / Red / Green / Silver
Almonds / 45 / 51 / 48
Peanuts / 55 / 50 / 48
No Nuts / 60 / 47 / 46
E’s / Red / Green / Silver
Almonds / (144)(160)/450 = 51.2 / (144)(148)/450 = 47.36 / (144)(142)/450 = 45.44 / 144
Peanuts / (153)(160)/450 = 54.4 / (153)(148)/450 = 50.32 / (153)(142)/450 = 48.28 / 153
No Nuts / (153)(160)/450 = 54.4 / (153)(148)/450 = 50.32 / (153)(142)/450 = 48.28 / 153
160 / 148 / 142 / 450

Picture of how ’s would be distributed if they were independent. The best evidence is in the right tail with area 5%.

NO

79. 2.0995 falls between 1.064 and 7.779 on the table with df = 4. So the p-value is between 10% and 90% (closer to 90%).

If there is no relationship, the chance we would get evidence as strong as or stronger than we got that there is some relationship is between 10% and 90%. This is assuming all conditions were met and the data were gathered properly.

80. unknown

81. all means equal

some difference

Recall: so

Airline V / Airline W / Airline X / Airline Y / Airline Z
data / 79, 84, 84, 87 / 72, 76, 72, 80, 72, 78 / 82, 84, 80, 77, 80 / 84, 85, 81, 87 / 75, 75, 75, 70, 70
/ 334 / 450 / 403 / 337 / 365
/ 27922 / 33812 / 32509 / 28411 / 26675
/ 4 / 6 / 5 / 4 / 5
/ / 75 / 80.6 / 84.25 / 73
/ 11 / 12.4 / 6.8 / 6.25 / 7.5

The biggest standard deviation is which is no more than double the smallest which is , so we are ok. (You do not have to check this on a test question.)

and

=

We look on theF table with 4 degrees of freedom on the top and 19 on the bottom (left side of table) to get . Note the right hand tail in the picture is 5%.

The answer is YES since 13.282 is to the right of 2.8951.

82. 5% or less

83. Summary of work from #20

or

Plugging in x = 250 we get y = 15.82.

A)

df = 14 – 2 =12

this is a left tail test YES

3.762

B) or

C) or

D) Plugging in x = 16000 we get y = -1178.03

. or

E) Its hilarious! Nonsense from such extrapolation.