Calculating The Rate of Doing Work

 

Understanding "Rate of Doing Work" in Primary School Math

In primary school math, the rate of doing work tells us how much of a task (like painting a wall or filling a tank) someone or something can complete in a single unit of time, such as 1 hour, 1 day, or 1 minute.

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The Formula

To solve these problems, we use one simple formula:

Rate of Work = Total Work Done ÷ Time Taken

Important Rule: In math, a single complete job is always represented as 1 whole. For example, if a person takes 5 days to complete a job, their daily rate of work is 1/5 of that job.

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Practice Questions and Solutions (Ascending Difficulty)

Question 1: Very Simple (Direct Rate)

John can paint a fence in 4 hours. What fraction of the fence can he paint in just 1 hour?

Solution:

• Total Work: 1 whole fence
• Total Time: 4 hours
• Calculation: Rate = 1/4

Answer: John can paint 1/4 of the fence in 1 hour.

Question 2: Simple (Finding Total Time)

A water pump can fill 1/5 of a swimming pool in 1 hour. How many hours will it take the pump to fill the entire pool?

Solution:

• Rate of Work: 1/5 of the pool per hour
• Total Work: 1 whole pool
• Calculation: Total Time = 1 ÷ (1/5) = 1 × 5 = 5 hours

Answer: It will take the pump 5 hours to fill the entire pool.

Question 3: Medium (Working Together)

Mary can clean a classroom in 3 hours, and Jane can clean the same classroom in 6 hours. If they work together, what fraction of the classroom will they clean in 1 hour?

Solution:

• Mary's 1-hour rate: 1/3 of the room
• Jane