Pages typed by one typist in 8 hours = (600/10) = 60 pages
Pages typed by one typist in one hour = 60/8 = 7.5 pages
5) The average of Sohan’s marks in 6 subjects is 74. If his average in five subjects excluding science is 70 ,what percentage marks he obtained in science?
Total marks in 5 subjects excluding science = 5 ∗ 70 = 350
Therefore, marks obtained in science would be = 444 – 350 = 94
6) Average age of a group of 30 boys is 16 years. A boy of age 19 leaves the group and a new boy joins the group. If the new average age of the group is 15.8 years, find the age of the new boy.
As per question, if we minus age of boy who leaves the group and so add the age of boy who joins the group the new average becomes = 15.8 years.
∴ (30*16-19+X)/30= 15.8
480 – 19 + X = 474
X = 474 – 480 +19
X = – 6 +19
= 13 years
Try to solve more problems on average.
7) The average weight of 10 men is decreased by 2 kg when one of them whose weight is 60 kg is replaced by a new man. What is the weight of the new man?
There are 10 men so total decrease in weight on replacing a man with a new man = 10 ∗ 2= 20 kg
Weight of the man who is replaced = 60 kg
∴The weight of the new man would be = Weight of man replaced – total decrease in weight of the group of 10 men.
= 60 – 20 = 40 kg
8)In a class the average age of 30 boys is 15 years. If we include the age of two teachers the average age increases by 1. Find the sum of ages of the two teachers.
Total age of 30 boys and 2 teachers would be = 32∗16= 512 years
∴ Sum of ages of two teachers would be = 512 – 450 = 62 years
9) The average age of the committee of 10 members is 40 years. A member of age 52 retires and a new member of age 38 takes his place. What is the average age of the present committee?
