Quantitative Aptitude - Arithmetic Ability Questions

In a class there were 28 boys and some girls. In a test the mean score obtained by the boys was 12.5 while that obtained by the girls was 14.5. If the overall average was 13.1, what was the total number of students in the class?

The sum of the present ages of two cousins is 46 years. Eight years ago, the elder one was twice as old as the younger one. What is the present age of the elder cousin?

A milk merchant buys 50 litres of milk at the rate of Rs 40 per litre and mixes 5 litres of water in it. If he sells this mixture at the rate of Rs 42 per litre, then what is the profit percentage for the dealer?

Simplify : 69 X 69 X 69 -65 X 65 X 669 X 69 + 69 X 65 + 65 X 65

Simplify: (213 x 213 + 187 x 187)

Ranjith can complete a task in 25 days while Anji can finish it in 20 days. They work together on the task for 5 days and then Ranjith leaves. In how many days will Anji finish the remaining work?

Amit can complete a work in 25 days and Punit can complete the same work in 20 days. Punit alone worked at it for 10 days and then left the work. In how many days will Amit alone complete the remaining work?

If x + y + z = 22 and xy + yz + zx = 35, then what is the value of (x – y)2 + (y – z)2 + (z – x)2?