Aptitude Day 169

Problems on Average:

          

1. Of the 3 numbers, the 1^st is half of the 2^nd, the 2^nd is 7 times of the 3^rd one. The average of the numbers is 92. The 2^nd smallest number is:

Solution:

                 Let the 3^rd number be x.

                

                 [x+ 7x +7x/2]/ 3 = 92

                 [2x+14x+7x]/2 = 92*3

                 23x = 92*6

                 x = 24.

                The numbers are x,  7x, 7x/2 = 24, 168 and 84.

                 The 2^nd smallest number is 84.

2. Of the 5 numbers whose average is 120, the 1^st is one-third of the sum of the last 4. The 1^st number is:

Solution:

                 Let the 1^st number be x.

                 Sum = 120*5 = 600.

                 x = 1/3(Sum of the last 4 numbers)

                 Sum of the last 4 numbers = 3x

                (x +3x)/5 = 120

                4x=120*5

                x = 150.