The average weight of 10 boys is increased by 3 kg if one of them weighing 40 kg is replaced by a new boy. The weight of the new boy is:
70 kg
Given:
Average weight of 10 boys.
Increase in average weight = 3 kg.
Weight of the boy being replaced = 40 kg.
Concept:
Change in average × Number of data points = Change in total weight.
Solution:
For 10 boys, the total weight increase due to the 3 kg average increase ⇒ 3 kg × 10 = 30 kg.
Difference in weight between the new boy and the boy being replaced ⇒ 30 kg + 40 kg (weight of the boy being replaced) = 70 kg.
Therefore, the weight of the new boy is 70 kg.
Important Questions from Average
The average height of 20 students of class 8 is 152 cm and the average height of 15 students of class 9 is 168 cm. What is the average height (to the nearest cm) of the students of both classes?
The average of 4, 6, 8, 12 and x is 7 and the average of x, 9, 13, 15 and y is 9. What is the value of 2x - 3y?
The average weight of 20 girls in a school was 52 kg. Two new students of weight 54 kg and 50 kg were admitted. The ratio of this new average to the old one is:
If the average of two numbers is 13 and the square root of their product is 12, then the difference between the numbers is:
If the average of 5 consecutive odd integers in increasing order is 11 , then the average of the last 3 of them is:
