The task is to generate the correct answer for a given math problem.

Problem: calculate the sum of first 60 natural numbers .
1830

Problem: set s contains exactly 10 numbers and has an average ( arithmetic mean ) of 6.2 . if one of the numbers in set s is increased by 7 , while all other numbers remain the same , what is the new average of set s ?
6.

Problem: an article is bought for rs . 805 and sold for rs . 900 , find the gain percent ?

11.8 %