: SI Exam: Do you have time to work on time and work problems? #IndiaNEWS #Education By Banda Ravipal Reddy Hyderabad: This article is in continuation to the last article on preparation for the Sub-Inspector

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SI Exam: Do you have time to work on time and work problems? #IndiaNEWS #Education
By Banda Ravipal Reddy
Hyderabad: 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 and B undertaken to do a work for Rs 6000. A alone and B alone can do not that in 6 and 8 days respectively. With the help of C, they have finished the work in 3 days. The share of B’s is (SI PRE 2018)
A. Rs 2,400 B. Rs 2,250 C. Rs 2,000 D. Rs 1,500
Ans: B
Explanation:
A = 6 days, B = 8 days and A B C = 3 days
Total work= LCM of (6, 8, 3) = 24
Efficiency of (A, B, A B C) = 4, 3 and 8
A B C=8
Efficiency of C = 8-4-3 = 1
Ratio of efficiency of A, B, C= 4: 3: 1
Total amount = 6000
B’s share = 6000×3/8= 2250
2. A piece of work can be completed by A, B and C individually in 12, 8 and 6 hours respectively. All the three worked for two hours at which point of time C left the work. The time (in minutes) taken by the other two to complete the work is: (SI PRE 2018)
A. 12 B. 24 C. 62 D. 72
Ans: D
Explanation:
A= 12 hours, B = 8 hours and C = 6 hours
Total work = LCM of (12, 8, 6) = 24
Efficiency of (A, B, C) = 2, 3 and 4
The work completed in two hours = (2 3 4) × 2= 18
Remaining work = 24-18 = 6 units
Time taken by A and B to complete 2 units of work = 6/5 hours= 72 min
3. Person A completes a work W1 in 6 hours while person B completes another work W2 in 6 hours. If W2 is only equal to two-thirds of W2 then the number of hours required for A and B together to complete both W1 and W2 is (SI PRE 2018)
A. 6 B. 7 C. 5 D. 8
Ans: A
Explanation:
Suppose W2 = 1
So, according to the question: W1= 2/3
Total work i. e. , W1 W2 = 1 2/3 = 5/3
Work done by A in one hour = (2/3)/6 = 1/9
Work done by B in one hour = 1/6
Total work done by A and B together in one hour = 1/9 1/6 = 5/18
Number of hours required for A and B together = (5/3)/(5/18) = 6
4. A and B can do a piece of work independently in 12 days and 16 days respectively. They worked together for 4 days and B left the work. How many more days A worked to finish the work? (SI PRE 2018)
A. 3 B. 4 C. 5 D. 6
Ans: C
Explanation:
A and Bs one days work =1/16 1/12 = (3 4)/48 = 7/48
(A B) 4 day’s work= 7/48×4 = 7/12
Remaining work 1-7/( 12) = 5/12
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