Statistics Refresher Sheet 1

Mean:Add all the numbers together then divide by how many numbers there are.

Median:Put all the numbers in order of size then find the middle one.

Mode:The number that occurs most often.

Range:The biggest number take away the smallest number.

Quartiles:Divides the data into 4 equal parts.

Standard Deviation:Measures the spread of the values in the data set (usually denoted by σ (sigma)).

σ =

Example:

Sum

Data Set: / 30 / 11 / 18 / 8 / 42 / 40 / 5 / 21 / 22 / 5 / 35

Mean = 237= 21.5Mode= 5Range = 42 - 5 = 37

5 5 8 11 18 21 22 30 35 40 42

Lower quartileMedianUpper Quartile

Standard Deviation:

Sum

= / 5 / 5 / 8 / 11 / 18 / 21 / 22 / 30 / 35 / 40 / 42
= / 25 / 25 / 64 / 121 / 324 / 441 / 484 / 900 / 1225 / 1600 / 1764 / 6973

σ = = = 13.1

H Jackson 2008 / Academic Skills 1

1)Jacqui saves monthly for her summer holiday.

Jan £50, Feb £60, Mar £50, Apr £50, May £66, June £60

Mean =

Mode =

Median =

Range =

2)One week the daily temperatures in an office were recorded as:

170C, 210C, 230C, 190C, 200C

Mean =

Mode =

Median =

Range =

3)A household receives the following numbers of letters over a week: 6, 3, 1, 9, 4 and 1.

Mean =

Mode =

Median =

Range =

4)One evening there were 5 classes running in a college, 3 had 15 students, 1 had 10 students and the last had only 7 students.

3