Aptitude Day 160

Problems on Average:

1. A library has an average of 400 visitors on Sundays and 130 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is:

Solution:

                The month has 5 Sundays since it begins with a Sunday.

                Average = [ 400(5) + 130(25)] / 30

                                = 5250/30

                                = 75.

2. If the average marks of these 3 batches of 40, 50 and 65 students respectively is 60, 65 and 70, then the average mark of all students is:

Solution:

                 Average = [40(60)+50(65)+65(70)]/ [40+50+65]

                                 = [2400+3250+4550]/ 155

                                 = 10200/155

                                 = 65.8.