Time and Work is a fundamental topic in mathematics that plays a vital role in real-life problem-solving and competitive exam preparation. This chapter has been carefully crafted by experienced subject matter experts to help students master two key areas:
- Determining the time needed to complete a given task
- Calculating the work accomplished within a specified period
Our team of qualified mathematics educators has designed the solutions in a clear, step-by-step format to ensure that learners of all levels can easily understand the methods involved. This approach helps build problem-solving confidence and equips students to score higher marks in school examinations as well as competitive tests.
The RD Sharma Class 8 Maths Solutions are recognised by educators across India as reliable, accurate, and exam-focused study materials. The explanations are detailed, error-free, and follow the latest syllabus, ensuring students receive high-quality academic guidance.
- Free PDF Access: Students can easily download the complete chapter solutions in PDF format from the trusted links provided on this page.
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Chapter 11 – Time and Work contains a single exercise that covers:
1. Time and Work Problems
- Finding the total time required to finish a task
- Calculating the amount of work done in a given time
2. Pipes and Cisterns Problems (special type of Time and Work problem)
These problems are solved with clear explanations, ensuring students not only learn the formulas but also understand the logic behind them.
RD Sharma Solutions Class 8 Maths Time and Work - Free PDF Download
Download free and comprehensive RD Sharma Solutions for Class 8 Mathematics Chapter 11 Time and Work, prepared by expert mathematics teachers. These step-by-step solutions cover all exercise questions from the chapter, helping you revise the complete syllabus effectively and score higher marks in your exams.
Whether you’re preparing for school assessments or competitive entrance exam like JEEMains & JEE Advanced, NEET, or other engineering and medical exams, these RD Sharma solutions provide a strong conceptual foundation in the Time and Work topic.
Access Answers to Maths RD Sharma Solutions for Class 8 Chapter 11
Q. Rohan can paint 1/3 of a painting in 6 days. How many days will he take to complete painting?
Solution: Given:
Rohan takes 6 days to paint 1/3 of the painting.
Calculation:
Time taken to complete the entire painting:
Total Days=6/1/3=6×3=18
Rohan can complete the entire painting in 18 days.
Q. Rakesh can do a piece of work in 20 days. How much work can he do in 4 days?
Solution: Given:
Time taken by Rakesh to complete the entire work = 20 days.
Work done in 1 day: 1/20
Work done in 4 days: 4 × 1/20 = 1/5
Rakesh can complete 1/5 of the work in 4 days.
Q. Anil can do a piece of work in 5 days and Ankur in 4 days. How long will they take do the same work, if they work together?
Solution: Given:
Anil can finish the work in 5 days.
Ankur can finish the work in 4 days.
Work done in 1 day: Anil = 1/5 of the work, Ankur = 1/4 of the work.
Combined 1-day work: 1/5 + 1/4 = 4/20 + 5/20 = 9/20 of the work.
Total time to complete the work together: 1 ÷ (9/20) = 20/9 days.
Convert to days and hours: 20/9 days ≈ 2 days + (2/9 × 24 hours) = 2 days 5 hours 20 minutes.
Working together, Anil and Ankur can complete the job in 2 days 5 hours 20 minutes.
Q. Mohan takes 9 hours to mow a large lawn. He and Sohan together can mow in 4 hours. How long will Sohan take to mow the lawn if he works alone?
Solution: Mohan’s rate = 1/9 lawn per hour
Together rate (Mohan + Sohan) = 1/4 lawn per hour
So Sohan’s rate = 1/4 − 1/9 = (9 − 4)/36 = 5/36 lawn per hour
Time for Sohan alone = 1 ÷ (5/36) = 36/5 hours = 7.2 hours
= 7 hours 12 minutes.
Sohan would take 7 hours 12 minutes working alone.
Q. Sita can finish typing a 100 page document in 9 hours, Mita in 6 hours and Rita in 12 hours. How long will they take to type a 100 page document if they work together?
Solution: Given:
Sita can type a 100-page document in 9 hours.
Mita can type it in 6 hours.
Rita can type it in 12 hours.
Work rates (in fraction of document per hour):
Sita = 1/9, Mita = 1/6, Rita = 1/12
Combined rate:
1/9 + 1/6 + 1/12 = 4/36 + 6/36 + 3/36 = 13/36
Time to complete together:
1 ÷ (13/36) = 36/13 hours ≈ 2.77 hours
Convert to hours and minutes:
2 hours + (0.77 × 60 minutes) ≈ 2 hours 46 minutes
Working together, Sita, Mita, and Rita can type the 100-page document in 2 hours 46 minutes.
Q. A, B and C working together can do a piece of work in 8 hours. A alone can do it in 20 hours and B alone can do it in 24 hours. In how many hours will C alone do the same work?
Solution: Given:
A, B, and C together can finish the work in 8 hours.
A alone can finish it in 20 hours.
B alone can finish it in 24 hours.
Individual 1-hour work:
A = 1/20, B = 1/24, A + B + C = 1/8
Find C’s 1-hour work:
1/8 − 1/20 − 1/24
Convert to common denominator (120):
15/120 − 6/120 − 5/120 = 4/120 = 1/30
Time for C alone:
1 ÷ (1/30) = 30 hours
C alone can complete the work in 30 hours.
Q. A and B can do a piece of work in 18 days; B and C in 24 days and A and C in 36 days. In what time can they do it, all working together?
Solution:
A + B can finish in 18 days → 1-day work = 1/18
B + C can finish in 24 days → 1-day work = 1/24
A + C can finish in 36 days → 1-day work = 1/36
(A + B) + (B + C) + (A + C) = (1/18) + (1/24) + (1/36)
This gives:
2A + 2B + 2C = LCM(18, 24, 36) = 72
Convert each to denominator 72:
-
1/18 = 4/72
-
1/24 = 3/72
-
1/36 = 2/72
Sum = (4 + 3 + 2)/72 = 9/72
So:
2(A + B + C) = 9/72
A + B + C = (9/72) ÷ 2 = 9/144 = 1/16
If they do 1/16 of the work in 1 day, they can finish in 16 days.
Final Answer: All three working together can complete the work in 16 days.
Q. A and B can do a piece of work in 12 days; B and C in 15 days; C and A in 20 days. How much time will A alone take to finish the work?
Solution: Given:
A and B can finish the work in 12 days → 1-day work = 1/12
B and C can finish the work in 15 days → 1-day work = 1/15
A and C can finish the work in 20 days → 1-day work = 1/20
(A + B) + (B + C) + (A + C) = 2(A + B + C)
2(A + B + C) = 1/12 + 1/15 + 1/20
LCM of 12, 15, 20 = 60 → (5 + 4 + 3)/60 = 12/60 = 1/5
(1/5) ÷ 2 = 1/10
A = (A + B + C) − (B + C) = 1/10 − 1/15
LCM of 10, 15 = 30 → (3 − 2)/30 = 1/30
Time for A alone:
1 ÷ (1/30) = 30 days
A alone can complete the work in 30 days.
Q. A, B and C can reap a field in 15 ¾ days; B, C and D in 14 days; C, D and A in 18 days; D, A and B in 21 days. In what time can A, B, C and D together reap it?
Solution: Given: A, B, C can reap the field in 15 3/4 days; B, C, D in 14 days; C, D, A in 18 days; D, A, B in 21 days. Find the time for A, B, C, D together.
Let 1-day works be: A = a, B = b, C = c, D = d.
Convert to daily rates:
A + B + C = 1 / (15 3/4) = 1 / (63/4) = 4/63
B + C + D = 1/14
C + D + A = 1/18
D + A + B = 1/21
Add all four equations:
3(a + b + c + d) = 4/63 + 1/14 + 1/18 + 1/21
Compute with LCM 126:
4/63 = 8/126, 1/14 = 9/126, 1/18 = 7/126, 1/21 = 6/126
Sum = (8 + 9 + 7 + 6)/126 = 30/126 = 5/21
Total combined rate:
a + b + c + d = (5/21) ÷ 3 = 5/63 (field per day)
Time for all four together:
Time = 1 ÷ (5/63) = 63/5 days = 12.6 days ≈ 12 days 14 hours 24 minutes
Answer: 63/5 days = 12 days 14 hours 24 minutes.
Q. A and B can finish a work in 20 days. A alone can do 1/5th of the work in 12 days. In how many days can B alone do it?
Solution: Given,
A and B can finish a work in = 20 days
(A+ B)’s 1 day work = 1/20
A can finish 1/5th of work in = 12 days
A’s 1 day work = 1/(5×12) = 1/60
We know that,
B’s 1 day work = (A+B)’s 1 day work – A’s 1 day work
= 1/20 – 1/60
= (3-1)/60
= 2/60
= 1/30
B alone can finish the work in = 1/(1/30) = 30days
Benefits of RD Sharma Solutions for Class 8 Maths Chapter 11
Here are the benefits of RD Sharma Solutions for Class 8 Maths Chapter 11 – Time and Work in clear points:
- Strong Concept Understanding – Explains Time and Work fundamentals in a simple, step-by-step manner, including real-life applications.
- Covers All Problem Types – Includes questions on both time to complete work and work done in a given time, as well as related topics like Pipes and Cisterns.
- Step-by-Step Solutions – Each problem is solved in a logical sequence, making it easy for students to follow and apply the same approach in exams.
- Exam-Focused Preparation – Solutions are aligned with CBSE guidelines, ensuring students practice in a way that helps them score better in school and competitive exams.
- Free PDF Access – Students can download the solutions for offline study without any cost barrier.
- Self-Assessment Tool – Helps students compare their answers with the provided solutions to identify mistakes and improve problem-solving accuracy.
- Boosts Speed and Accuracy – Regular practice with these solutions improves time management during exams.
- Prepared by Experts – Content is created by experienced mathematics teachers, ensuring correctness and clarity.
Frequently Asked Questions
Ans. RD Sharma Soltutions Chapter 11 covers:
- Calculating the time required to finish a given work.
- Finding the amount of work completed in a given time.
- Solving combined work problems involving two or more people.
- Related concepts like Pipes and Cisterns.
Ans. Yes, the solutions are prepared as per the CBSE syllabus and exam pattern. They include step-by-step explanations, making it easier for students to understand concepts, revise effectively, and score higher marks in school exams.
Ans. Yes, the solutions are available in PDF format for free download. Students can save them for offline study and revise anytime without an internet connection.
Ans. The solutions are prepared by expert mathematics teachers with years of experience. They ensure that all answers are accurate, conceptually clear, and follow the NCERT/CBSE guidelines.
Ans. The solutions use a structured approach starting with identifying the given data, calculating work rates, and applying formulas with proper LCM/fraction simplifications. This helps students grasp the logic behind each step and apply the method to similar problems confidently.