Aptitude Day 158

Problems on Average:

1. The sum of 3 consecutive odd numbers is 10 more than the average of these numbers. What’s the  1^st of these numbers?

Solution:

                   [x+(x+2)+(x+4)] - [x+(x+2)+(x+4)]/ 3 = 10

                   (3x+6)-(3x+6)/3 = 10

                   (33x+6)(2/3) = 10

                   3x+6 = 15

                   x =3.

2, The average age of the boys in a class is 10 years and that of the girls is 9 years. The average age of the whole class is:

Solution:

                 In order to find the average, we’ve to know the number of boys and girls in the class. Since we don’t have either the number of girls and boys in the question, we couldn’t able to find the average age. The data is inadequate.