Page 1 - Lession note - stat chap -9,MCT (AM)-50

Class-XI

STATISICS

CHAPTER-Measures of Central Tendency

Topic –Arithmetic Mean (Module-50)

Missing values ,Special cases –Inclusive classes ,Mid value series

,cumulative series

Short note

Arithmetic Mean
Arithmetic Mean is the number which is obtained by adding the values of
all the items of a series and dividing the total by the number of items.

Examples 1:- Find the missing frequency if AM of the following is 33

X 0-10 10-20 20-30 30-40 40-50 50-60
f 10 15 30 ----- 25 20

Ans : 25

Examples 2:- Find the AM of the following .(Inclusive series )

X 50-59 40-49 30-39 20-29 10-19 0-9
f 4 2 3 5 4 3

Examples 3:- Find the AM of the following.(Mid value series)

X 54.5 44.5 34.5 24.5 14.5 04.5
f 4 2 3 5 4 3

Examples 4:- Find the AM of the following .(Cumulative series –less than )

X Less than 5 < 10 <15 < 20 < 25
f 2 5 9 12 14

Examples 5:- Find the AM of the following. (Cumulative series –more than )

X More than 5 >10 >15 >20 >25
f 14 12 9 5 2