Q3 of 25 Page 332

The following distribution shows the daily pocket allowance of children of a locality. The mean pocket allowance is ` 18. Find the missing frequency f.

To find f, we’ll need to find mean pocket allowance by direct method and equate it to the given mean pocket allowance, 18.

So, let’s construct a table finding midpoints and stating frequencies.



Mean is given by



⇒ [given, mean = 18]


⇒ 18(44 + f) = 752 + 20f


⇒ 792 + 18f = 752 + 20f


⇒ 20f – 18f = 792 – 752


⇒ 2f = 40


⇒ f = 40/2


⇒ f = 20


Thus, the missing frequency f is 20.


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1

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 2

Consider the following distribution of daily wages of 50 workers of a factory.


Find the mean daily wages of the workers of the factory by using an appropriate method.

 4

Thirty women were examined in a hospital by a doctor and their of heart beats per minute were recorded and summarized as shown. Find the mean heart beats per minute for these women, choosing a suitable method.

 5

In a retail market, fruit vendors were selling oranges kept in packing basket. These baskets contained varying number of oranges. The following was distribution of oranges.


Find the mean number of oranges kept in each basket. Which method of finding the mean did you choose?