When 15 is included in a list of natural numbers, their mean is increased by 2. When 1 included in this new list, the mean of the numbers in the new list is decreased by 1. How many numbers were there in the original list?

(a) 4 (b) 5 (c) 6 (d) 8

When 15 is included in a list of natural numbers, their mean is increased by 2. When 1 included in this new list, the mean of the numbers in the new list is decreased by 1. How many numbers were there in the original list?

(a) 4 (b) 5 (c) 6 (d) 8

1 Answer

127 votes

Let there be numbers in the original list and let their mean be

Then, sum of numbers =

And,

Solving we get

127 votes

127