A and B can do a piece of work in 30 days and 36 days respectively. They began the work together but A left after some days and B finished the remaining work in 25 days. After how many days did A leave? MCQ with Answer and Explanation

A and B can do a piece of work in 30 days and 36 days respectively. They began the work together but A left after some days and B finished the remaining work in 25 days. After how many days did A leave?
A. 5 days
B. 6 days
C. 8 days
D. 4 days
Answer: Option A
Solution (By JKSSB Mock Tests)
Total work = LCM(30, 36) = 180 units. Efficiency of A = 6, B = 5. B worked alone for 25 days: work done = 25 * 5 = 125 units. Remaining work = 180 - 125 = 55 units. This was completed by A and B together. Combined efficiency = 11. Days worked together = 55 / 11 = 5 days. Thus, A left after 5 days.

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Practice More Time and Work Questions

Question #1
A contract is to be completed in 46 days and 117 men were set to work, each working 8 hours a day. After 33 days, 4/7 of the work is completed. How many additional men may be employed so that the work may be completed in time, each man now working 9 hours a day?
A. 80
B. 81
C. 83
D. 82

Correct Answer: Option B


Explanation:
Remaining days = 46 - 33 = 13 days. Remaining work = 1 - 4/7 = 3/7. Using (M1 * D1 * H1) / W1 = (M2 * D2 * H2) / W2: (117 * 33 * 8) / (4/7) = (M2 * 13 * 9) / (3/7) => (117 * 33 * 8) / 4 = (M2 * 13 * 9) / 3 => 117 * 33 * 2 = M2 * 13 * 3 => 117 * 33 * 2 = 39 * M2 => M2 = (117 * 33 * 2) / 39 = 3 * 33 * 2 = 198 men. Additional men = 198 - 117 = 81.

This question belongs to: Maths Time and Work
Question #2
12 men can complete a work in 8 days. How many days will 16 men take to complete the same work?
A. 6 days
B. 5 days
C. 7 days
D. 4 days

Correct Answer: Option A


Explanation:
Using the formula M1 * D1 = M2 * D2: 12 * 8 = 16 * D2. 96 = 16 * D2. D2 = 96 / 16 = 6 days.

This question belongs to: Maths Time and Work
Question #3
A can complete a work in 18 days. What percentage of work will A complete in 6 days?
A. 38.33
B. 33.33
C. 43.33
D. 48.33

Correct Answer: Option B


Explanation:
Percentage completed = (6/18) × 100 = 33.33%.

This question belongs to: Maths Time and Work