Time and Work – Concept, Formula & Aptitude Questions for bank exams

Understanding the concepts of time and work is crucial for success in bank exams. These topics frequently appear in the quantitative aptitude section, testing a candidate’s ability to allocate resources and manage tasks efficiently.

Time and Work

Time and Work problems are a staple in many competitive exams, including bank exams. These problems assess a candidate’s ability to analyze the relationship between time, work, and efficiency. Mastery of this topic can significantly enhance your performance in the quantitative section of bank exams. This article will delve into the core concepts, essential formulas, and typical aptitude questions you may encounter.

Concepts of Time and Work

Work and Time Relationship:

• Work: Generally considered as a task or a job that needs to be completed.
• Time: The duration required to complete the work.

Efficiency (Rate of Work): This is typically the amount of work done per unit of time. Higher efficiency means less time is required to complete the work.

Basic Principles:

• If a person or a machine can complete a job in ‘n’ days, then the amount of work done in one day is 1/n of the total work.
• Conversely, if a person or machine can do 1/n of the work in one day, they can complete the work in ‘n’ days.

Combined Work:

When multiple people or machines work together, their combined rate of work is the sum of their individual rates.

Essential Formulas

Individual Work Rate:

• Work rate of A = 1\Time taken by A to complete the work

Combined Work Rate:

• Work rate of A and B = Work rate of A + Work rate of B

Time Taken by Combined Workers:

Time taken by A and B together = 1\ (Work rate of A + Work rate of B)

Work Equivalence:

• If A is ‘k’ times as efficient as B, then A will take ‘1/k’ times the time B takes to complete the work.

Work Done by Multiple Entities:

• If A, B, and C can do a piece of work in x, y, and z days respectively, the combined work rate is:

Combined work rate = 1/x + 1/y + 1/z

• The time taken by A, B, and C together to complete the work is:
  Time taken = 1\Combined work rate

Aptitude Questions for Practice

Question 1:

A can complete a work in 12 days, and B can complete the same work in 16 days. How long will it take for A and B to complete the work together?

Solution:

Work rate of A = 1/12

Work rate of B = 1/16

Combined work rate = 1/12 + 1/16 = (4 + 3)/48 = 7/48

Time taken = 48/7 (approx 6.86) days.

Question 2:

If A is twice as efficient as B and together they can complete a work in 18 days, how long will it take for each to complete the work individually?

Solution:

Let B’s work rate be 1/x. Then, A’s work rate is 2/x

Combined work rate = 1/x} + 2/x = 3/x.
3/x = 1/18

x = 54
Time taken by B = 54 days, and by A = 54/2 = 27 days.

Question 3:

C can do a job in 10 days. B is 50% more efficient than C, and A is twice as efficient as B. How long will it take for A, B, and C together to complete the job?

Solution:

Work rate of C = 1/10.
Work rate of B = 1.5 × (1/10) = 3/20

Work rate of A = 2 × (3/20) = 3/10

Combined work rate = 1/10 + 3/20 + 3/10 = 2/20 + 3/20 + 6/20 = 11/20

Time taken = 20/11 (approx 1.82) days.

Tips for Solving Time and Work Problems

Understand the Question: Carefully read the problem to identify who is working, their individual work rates, and how these rates combine.

Use Ratios and Proportions: Many problems can be simplified using ratios, especially when comparing efficiencies.

Work with Fractions: Be comfortable converting work and time into fractions, as most solutions involve fractional rates of work.

Practice Regularly: Frequent practice helps in recognizing patterns and improving speed and accuracy.

By mastering these concepts, formulas, and practicing a variety of questions, you will be well-prepared to tackle the Time and Work problems in your bank exams.