Question

15 boys earn Rs900 in 5 days. How much will 20 boys earn in 7 days?

Answer 1

Hint: To solve this problem we should know about basic mathematics and how to solve work and time problems.
Work & time: Work and time deals with the individual or a group of individuals to complete a piece of work and the efficiency of the work done by each of them. The number of units of work done per unit time is known as the rate of work. Rate of work and time are inversely proportional to each other.

Complete step by step solution:
Given,
15 boys earn Rs900 in 5 days
So,
15 boys earn how much in 1 day$ = \dfrac{{900}}{5}$
Now
1 boy earn how much in 1 day$ = \dfrac{{900}}{{15 \times 5}}$
Simplify the equation,
1 boy earns $Rs.12$ in 1 day.
According to the question.
If 1 boy earn in 1 day=$Rs.12$
So, 20 boys earn in 1 days=$Rs.12 \times 20$
Then 20 boys earn in 7 days=$Rs.12 \times 20 \times 7$
Simplify the equation
20 boys earn in 7 days=$Rs.1680$

Therefore, 20 boys earn $Rs.1680 $ in7 days..

Note:
The relation between days taken by individuals to complete a given work independently and to complete while working simultaneously or alternately. Teams of men, women, and children or time taken by the team to complete work independently or simultaneously. It helps us to find the efficiency of workers and work.