Query Detail : RBI Grade B Phase I

A student finds the average of five two digits numbers. If one number is reversed and the average is taken again then the average decrease by 7.2. If all the five digits are consecutive multiples of 5. Find the number that was reversed.
Abhik,   September 17th 2020,  
RBI Grade B Phase I


Let the number be ‘10a+b’.

If it is reversed then the number becomes ‘10b+a’.

ATQ,

10b + a − 10a – b = 5 × 7.2

⇒ 9b – 9a = 36

⇒ b – a = 4

Numbers can be 15, 26, 37, 48 and 59 but all the five digits are multiple of 5.

Therefore the number must be 15.