Question

4
For the data shown in the following table, x has a mean of 7.15.
3
6
10
15
Frequency
b
d
a
Find the mean value of y given in the following table.
11
14
18
23
Frequency
a
b
C
d
b) Find a calculated estimate of the mean value of a given in the following table.
2-
8-
14-
24-34
Frequency
b
с
d​

Answer 1

Answer:

To find the mean, first we have to find the mid-point of each class interval. Mid-point of each class interval. Mid-point of 0−4=(0+4)/2=2; mid-point of 5−9=(5+9)/2=7 and the like. Denote the mid-point of the class interval by x. Write down the frequencies f corresponding to each class interval.

Class interval Mid-point of CI (x) Frequency (f) fx

0−4 2 3 6

5−9 7 5 35

10−14 12 7 84

15−19 17 4 68

20−24 22 6 132

N=25 ∑fx=325

Multiply f and x to get fx. Add all fx and find out ∑fx. Now the mean is calculated using the formula.

X

=

total number of scores

sum of all scores

=

N

∑fx

Thus we get

X

=

N

∑fx

=

25

325

=13.

Therefore mean is 13.