Aptitude Day 163

Problems on Average:

1. The average of 30 numbers is 20. If 2 numbers 10 and 50 are discarded, then the average of the remaining numbers is:

Solution:

                Sum of observations = 20*30 = 600.

                600-10-50 = 540.

               

                New average = 540/28 = 19.29.

2, The average of 10 numbers is 30. If one number is excluded, the average becomes 27. The excluded number is:

Solution:

                 Sum of observations = 30*10 = 300.

                After excluding the sum will be = 27*9 = 243.

                The excluded number = 300-243 = 57.