The table below shows children in a class sorted according to their weights.

The mean weight is calculated as 26 kilograms. How many children have weights between 23 and 25 kilograms?

Given: mean weight = 26 Kg

Let the unknown weight is x.

Mean age of child = Total age/ total number of children

⇒ 560 + 24x = 26(21 + x)

⇒ 560 + 24x = 546 + 26x

⇒ 560 - 546 = 26x – 24x

⇒ 14 = 2x

⇒ x = 7

children have weights between 23 and 25 kilograms = 7

Total number of questions = 12

How much each question will cost?