Quantitative Aptitude Questions( Averages) for IBPS RRB PO & Clerk Exam

1. The average age of 24 students and the principal is 15 years. When the principal’s age is excluded, the average age decreases by 1 year. What is the age of the principal?
(a) 38 
(b) 40
(c) 39 
(d) 37