Question

The mean of the following distribution is 62.8 and the sum of all the frequencies is 50 . Find the missing frequencies

Answer 1

Answer:

[given: ∑fi = 50]

⇒ 62.8(50) = 2060 + 30f1 +70f2

⇒ 3140 = 2060 + 30f1 +70f2

⇒ 3140 - 2060 = 30f1 +70f2

⇒ 1080 = 30f1 +70f2

⇒ 108 = 3f1 +7f2 …(i)

and 30 + f1 +f2 = 50

⇒ f1 +f2 = 50 – 30

⇒ f1 +f2 = 20

⇒ f1 = 20 – f2 …(ii)

Now, putting the value of f1 in eq. (i), we get

3(20 –f2) + 7f2 = 108

⇒ 60 – 3f2 + 7f2 = 108

⇒ 4f2 = 108 – 60

⇒ 4f2 = 48

⇒ f2 = 12

Now, substitute the value of f2 in eq. (ii), we get

f1 = 20 – 12

⇒ f1 = 8