A sum of RS 700 have to be used to give seven cash prizes to the students of a school for their over...........

Quantitative Aptitiude (CLAT) Number System

A sum of RS. 700 have to be used to give seven cash prizes to the students of a school for their overall academic performance. If each prize is Rs. 20 less than its preceding prize, then what are the least value of the prize?

RS. 30

RS. 40

RS. 60

RS. 80

Explanation:

Let the least value price be X. Then the next value is X+20, and the next value is X+40 and on and on up to 7 values. It’s nothing but an arithmetic Progression with sum 700. You can do it either manually or using the formula of AP. Technique 1: (Manually) X + X+20 + X+40 +… X+120=700 => 7X+(20+40+…+120)=700 => 7X+20(1+2+3+…+6)=700 => 7X+20(21)=700 => 7X=280 =>X=40