Meta Description: Learn time and work problems easily with formulas, shortcuts, solved examples, and practice questions. Best maths guide for students.
Introduction
Time and Work is an important maths topic for school students and competitive exams. It helps calculate how much time a person or group takes to complete a job.
In this lesson, you will learn time and work problems in a simple and easy method.
What is Time and Work?
Time and Work means finding how long work takes to finish based on speed of workers.
Basic rule:
- More workers = Less time
- Less workers = More time
Basic Formula
Work = Time x Efficiency
If work is fixed:
Work = Total job to be done
Time = Time taken
Efficiency = Work done per unit time.
Example 1: One Person Work
A can complete a job in 10 days.
So, one day work of A: 1/10
This means A finishes one-tenth work per day.
Example 2: Two Persons Together
A can do work in 10 days.
B can do work in 15 days.
One day work:
A= 1/10 , B= 1/15
Together:
=1/10 + 1/15
= 5/30
= 1/6
So total work per day =1/6
Therefore time taken: 6 days
Example 3: Three Workers
A = 12 days, B = 18 days, C = 36 days
One day work:
A= 1/12 , B= 1/18 , C= 1/36
=1/12 + 1/18+ 1/36
= 3+2+1/36
= 1/6
Time taken together =6 days
Shortcut Trick
If two people take a days and b days:
Together time =a x b/a+b
Example: a= 10 days b=15 days
Together time = 10 x 15 /10+15
= 150/25
= 6 days
Real Life Uses
- Construction work
- Cleaning tasks
- Factory production
- Group projects
- Farming work
Practice Questions
- A can finish work in 8 days. One day work = ?
- A = 10 days, B = 10 days. Together time = ?
- A = 6 days, B = 3 days. Together time = ?
- A = 20 days, B = 30 days. Together time = ?
Answers
- 5 days
- 2 days
- 12 days
Common Mistakes
- Adding days directly instead of work rates
- Wrong LCM in fractions
- Forgetting to invert final answer
Conclusion
Time and Work becomes easy when you use one day work method. Practice regularly to improve speed in exams.
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