Let’s focus on arithmetic QnA
Hyderabad: Let’s calculate the amount of time you take to solve these problems This article is in continuation to the last article on preparation for the Sub-Inspector of Police recruitment exam. Here are some previous year questions and explanations on the Time and Work topic. To improve calculations speed, the aspirants must practice questions from […]
Published Date - 16 May 2022, 11:17 PM
Hyderabad: Let’s calculate the amount of time you take to solve these problems This article is in continuation to the last article on preparation for the Sub-Inspector of Police recruitment exam. Here are some previous year questions and explanations on the Time and Work topic. To improve calculations speed, the aspirants must practice questions from the previous question papers.
1) A person A taken 7 1/2 days to finish 5th/8 of a work then the number of days required for A to finish the complete work is (SI MAINS 2018)
A. 9 B.12 C. 15 D. 18
Ans: B
Explanation:
Time required to complete the total work is = (15⁄2)/(5⁄8) = 12
=>; A can complete the work in 12 days
2) A person P can complete a work in 40 days. A second person Q can complete the same work in 35 days. Both P and Q work together for 14 days and then P goes away. The number of days that Q taken to complete the remaining work is (SI MAINS 2018)
A. 12 1/4 B. 10 1/2 C. 9 3/4 D. 8 3/4
Ans: D
Explanation:
Let total work be 280 units. ( LCM of 40,35)
Hence, P completes 7 units/day and Q completes 8 units/day
Total work done per day working together = 15 units
Total work done in 14 days together = 15× 14 = 210 units
Remaining work = 280-210 = 70 units
Time taken by Q to complete the remaining work = 70/8 = 8 3/4
3. Twenty men complete a work in 16 days. Twenty women complete the same work in 18 days. If all these men and women work together, then the number of days required to complete that work
(SI MAINS 2018)
A. 10 1/3 B. 9 8/17 C. 9 1/15 D. 8 8/17
Ans: D
Explanation:
20 men do a work in 16 days
20 men do 1/16 part of work in one day
20 women do 1/18 part of work in one day
Together they do 1/16 1/18 = 17/144 part in one day
Together the work is completed in 144/17 days= 8 8/17 days
4. A person A can complete a work in 15 days working 8 hours daily. A second person B can complete the same work in 20 days working 7 hours a day. If both A and B work together, working 7 hours a day, then the number of days required to complete that work is (SI MAINS 2018)
A. 8 5/13 B. 9 3/(13 ) C. 9 6/13 D. 10 1/4
Ans: B
Explanation:
Time taken by A = 15 × 8 = 120 hours
Time taken by A = 20 × 7= 140 hours
Total work = LCM of (120, 140) = 840 units
So A can complete 7 units and B can complete 6 units per hour
Together they can complete 13 units per hour
No. of units completed in a day = 13*7 = 91
No. of days required to complete the work = 840/91 = 9 3/(13 ) days
5. Two persons A and B can do a work in 24 and 30 days respectively. After working together for some days, A left. B finished the remaining work in 12 days. Then, the number of days that A worked is (SI MAINS 2018)
A. 8 B. 9 C. 10 D. 11
Ans: A
Explanation:
Let A work for x days with B
B = (x 12) days
x/24 (x 12)/30 = 1
5x 4x 48 =120
9x = 72
x = 8 days
-Banda Ravipal Reddy
Director, SIGMA
Sai Institute of General Mental Ability
Hyderabad