Statistics: Mean, Median & Mode JSS1 Mathematics Lesson Note

STATISTICS: AVERAGE, MEAN, MEDIAN, AND MODE

Average is a single value used to represent a set of numbers (i.e, all values in a set of data)

The most commonly used statistic is the average.

MEAN = SUM OF THE VALUES/NUMBER OF VALUES

MEDIAN = THE NUMBER IN THE MIDDLE AFTER THE ARRANGEMENT OF THE DATA IN INCREASING OR DECREASING ORDER

MODE = THE VALUE THAT OCCURS MOST FREQUENTLY.

EXAMPLES: Calculate the mean, median, and mode of the following data

45, 50, 55, 54, 48, 53, 50, 55

38, 35, 36, 30.8, 34.7, 37.9, 33.1

3, 0,4,7, 0, 5, 3, 4, 0, 3, 6, 5, 5,4, 6, 5

Solution: MEAN=(∑fx)/n i.e the addition of all the given items, divided by the number of items

Mean = 45+50+ 55+ 54+ 48+ 53+ 50+ 55

                                        8

= 410/8

= 51.25

Median = 45, 48, 50, 50, 53, 54, 55, 55

50 + 53

  2

= 52

Mode = Bimodal, which are 50 and 55 

FREQUENCY TABLE: The figure below represents the number of children per family in a sample of 40 houses in a street. 

1, 2, 4, 3, 5, 38, 3, 2, 2, 3, 4, 5, 6

5, 4, 2, 1, 3, 2, 4, 5, 3, 8, 7, 6, 5, 4

5, 7, 6, 3, 8, 6, 3, 5, 7, 5, 4, 3 

Prepare a frequency table to represent the information. 

Draw a bar chart to represent the information

A BAR CHART SHOWING THE NO OF CHILDREN PER FAMILY IN A SAMPLE OF 40 HOUSES

Frequency

10

9

8

7

6

5

4

3

2

1

0

      1         2         3      4 5       6 7     8  

No. of children per family

Do these

Exercise 24.1 pg 263 No (2, 4, 5,& 6)

Exercise 24.3 pg 266 No (3 & 4)