If mean of given data is 21, then value of p is:
x | 10 | 15 | 20 | 25 | 35 |
f | 6 | 10 | p | 10 | 8 |
We know, mean of a frequency distribution is calculated by:
¯¯¯x=∑fixi∑fi.
Given
mean ¯¯¯x=21.
∑fixi =(10×6)+(15×10)+(20×p)+(25×10)+(35×8)
=60+150+20p+250+280
=740+20p.
& ∑fi=6+10+p+10+8
=34+p.
Then,
⟹
21=740+20p34+p
⟹ 21(34+p)=740+20p
⟹ 714+21p=740+20p
⟹ 21p−20p=740−714
⟹ p=26.
Thus, option C is correct.