MeanMedianModeRange

What do they

all mean?

NEED TO KNOW!

ALWAYS ARRANGE THE VALUES IN A DATA SET IN ASCENDING (LEAST TO GREATEST) ORDER BEFORE

SOLVING FOR RANGE, MODE, MEDIAN AND MEAN.

Range• measure of dispersion (spread)• obtained by subtracting the smallest value

from the largest value

14, 17, 17, 21, 25, 28, 28, 28, 33highest value = 33

lowest value = 14range = 33 – 14 = 19

Central Tendency• single numerical value used to describe the

average or typical value in a set of values• 3 measures of central tendency– mode– median– mean

Mode• most frequent or popular value in a data set• determined by inspection

14, 17, 17, 21, 25, 28, 28, 28, 33mode =

(get 28 three time, get 17 twice and all other values only once)28

Median• counting average• the middle score

14, 17, 17, 21, 25, 28, 28, 28, 33median =

With an odd number of values, the median is the middle value. However, with an even number of values, there are two middle values. Since the median can only be a single value, the median will have to be calculated with an even number of values. How

can this be done?

25

Median cont’d• to figure out the median with an even number

of values– find the two middle values– find the average of these values by adding the two

values together and dividing by two

14, 17, 17, 19, 21, 25, 28, 28, 28, 33two middle numbers = 21 & 25

21 + 25 = 46median = 46 ÷ 2 = 23

Mean• arithmetic average• most widely used measure of central tendency• calculate by adding all the values together and

dividing by the number of values

14, 17, 17, 21, 25, 28, 28, 28, 3314+17+17+21+25+28+28+28+33 = 211

mean = 211 ÷ 9 = 23.4

REMEMBERALWAYS ARRANGE THE VALUES IN A DATA SET IN ASCENDING (LEAST TO GREATEST)

ORDER BEFORE SOLVING FOR RANGE, MODE, MEDIAN AND MEAN.

LET’S

PRACTICE

• Find the range, mode, median and mean of this data set.21, 18, 26, 30, 15, 26, 12, 18, 29, 26, 14, 23

First arrange the numbers in ascending order…12, 14, 15, 18, 18, 21, 23, 26, 26, 26, 29, 30

range = 30 – 12 = 18mode = 26

median = 21 + 23 = 44 ÷ 2 = 2212+14+15+18+18+21+23+26+26+26+29+30

12mean = 258 ÷ 12 = 21.5

NOW FOR

A STORY

PROBLEM…

• Amy works for a record store. For the past two weeks, she has kept track of the number of records that have sold each day.

• Find the range, mode, median and mean of this data.

WEEK 1 WEEK 2

SUNDAY 15 17

MONDAY 19 18

TUESDAY 20 22

WEDNESDAY 19 19

THURSDAY 24 28

FRIDAY 29 30

SATURDAY 26 25

Answers• Put the numbers in order…15, 17, 18, 19, 19, 19, 20, 22, 24, 25, 26, 28, 29, 30

range = 15mode = 19

median = 21mean = 22.2