Question

if the frequency distribution 5,10,?,5,15 has a mean of 10,then the missing number is?

Answer 1

Explanation:

Given frequency =120

⇒17+f

1

+32+f

2

+19=120

⇒f

1

+f

2

=52

Mean =

∑f

i

∑x

i

f

i

⇒mean =

120

(10×17)+(30×f1)+(50×32)+(72×f2)+(90×19)

⇒mean =

120

170+30f

1

+1600+70f

2

+1710

=50

⇒3f

1

+7f

2

=252

⇒3f

1

+7(52−f

1

)=252

⇒f

1

=28

⇒f

2

=24