RS Aggarwal Solutions Class 9 Mathematics Solutions for Mean Median And Mode Of Ungrouped Data Exercise 18B in Chapter 18 - Mean Median And Mode Of Ungrouped Data

Question 13 Mean Median And Mode Of Ungrouped Data Exercise 18B

Find the value of p, when the mean of the following distribution is 20.

x f
15 2
17 3
19 4
20 + p 5p
23 6

x f xifi
15 2 30
17 3 51
19 4 76
20+p 5p 100p + 5p2
23 6 138

It is given that

Mean = 20

We know that

Mean = Σ fi xi/ Σ fi

So we get

(5p2 + 100p + 295)/ (15 + 5p) = 20

On further calculation

5p2 + 100p + 295 = 300 + 100p

So we get

5p2 = 5

By division

p2 = 1

By taking square root

p = 1

Therefore, the value of p is 1.

1. The mean of the following distribution is 50.
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