Aptitude Day 149

Average:

Introduction:

Average = Sum of observations/ Number of observations

If a man covers a certain distance at x km/hr and an equal distance at y km/hr. Then, the average speed during the whole journey is (2xy/x+y) km/hr.

Problem:

Find the average of all prime numbers between 20 and 40.

Solution:

                 Average = Sum of observations/ Number of observations

                                 = ( 23+ 29+ 31+ 37 )/ 4

                                 = 120/4

                                 = 30.