Question

The mean of the following frequency distribution is 47. Find the value of ‘p’.


Classes 0 - 20 | 20 - 40| 40 - 60 |60 - 80 |80 - 100


Frequency 8 | 15 | 20 | p | 5
(class 10 CBSE SAMPLE PAPER 2017-18 MATHS)

Answer 1

In this question we find the mean by direct method.

In this method find the class marks of class interval. These class marks would serve as the representative of whole class and are represented by xi. For each class interval we have the frequency fi corresponding to the class mark xi.

Class marks=( lower limit + upper limit)/2

Then find the product of fi, & xi for each class interval. Find Σ fi & Σfixi.

Use the formula :

Mean = Σfixi/ Σfi

[SOLUTION IS IN THE ATTACHMENT]


HOPE THIS WILL HELP YOU...

Answer 2

Mean=47.3

Sum of f1=48+q

Sum of f1x1=1980+70q

Mean=47.3=1980+70q/48+q

=2270.4+47.3q=1980+70q

=-22.7q=-290.4

Q=-290.4/-22.7

Q=12.79