Aptitude Day 164

Problems on Average:

1. The average age of 20 students in a class is 12 years. The average age of 10 students is 11 years. What’s the average age of the remaining 10 students?

Solution:

                 1^st sum = 12*20 = 240.

                 2^nd sum = 11`*10 = 110.

                The average age of the remaining 15 students = (240-110)/10

                                                                                            = 130/ 10

                                                                                            = 13 years.

2. 15 children are too be divided into 2 groups A and B of 10 and 5 children. The average percentage marks obtained by the children of group A is 80 and the average percentage marks obtained by all the 15 children is 81. The average percentage marks obtained by the children of group B is:

Solution:

                1^st Sum = 81*15 = 1215

                2^nd Sum = 80*10 = 800.

 

               The average age of the remaining 5 students = (1215-800)/5

                                                                                       = 415/ 5

                                                                                       = 83.