Pravin can do a piece of work in 6 hours. Rishi can do it in 28 hours. With the assistance of Shan, they completed the work in 4 hours. In how many hours can Shan alone do it?
21
Work done by Pravin in 1 hour = 1/6, Rishi in 1 hour = 1/28.
Together, they complete the work in 4 hours, so total work done in 1 hour is 1/4.
Work done by Shan in 1 hour = 1/4 − (1/6 + 1/28) = 1/4 − 8/84 = 1/4 − 2/21 = 5/42.
Therefore, Shan alone can do the work in 42/5 = 21 hours.
Important Questions from Work and Wages
A and B can complete a piece of work in 120 days. B and C can complete it in 150 days, and A and C can complete it in 200 days. In hoe many days can B alone complete two-fifths of the same work ?
A book has 250 pages. Person A reads 6 pages in an hour. Person B reads 8 pages in an hour. There are two chapters of 72 pages that are difficult for person B to read in the book, so person B takes double the time to read those pages. Who among them will finish the book first and how much sooner than the other?
Efficiencies of P, Q, R and S in doing a job are in the ratio 2 : 3 : 5 : 4. The wages paid for the job are Rs.4200. Who is paid the largest amount and how much is paid?
P and Q can complete a job in 6 and 8 days individually. They both finish the job with the help of R in 3 days. How much wages are to be paid to R. if the total wages are Rs. 3200?
Anjali can do a certain piece of work in 16 days. Anjali and Ayushi can together do the same work in 10 days, and Anjali, Ayushi and Ankita can do the same work together in 8 days. In how many days can Anjali and Ankita do the same work?
