How i solve this problem of question no.3 of class 10th of ncert math of statistics chapter give me the best and the easy way for the answer of this question of exercise 14.1 of 3rd question The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is Rs 18. Find the missing frequency f.
To find out the missing frequency, use the mean formula.
Here, the value of mid-point (xi) mean x̄ = 18
The mean formula is
Mean = x̄ = ∑fixi /∑fi = (752+20f)/(44+f)
Now substitute the values and equate to find the missing frequency (f)
⇒ 18 = (752+20f)/(44+f)
⇒ 18(44+f) = (752+20f)
⇒ 792+18f = 752+20f
⇒ 792+18f = 752+20f
⇒ 792 – 752 = 20f – 18f
⇒ 40 = 2f
⇒ f = 20
So, the missing frequency, f = 20.