SSC CGL Work and Efficiency Practice Test 1

1. A can do a work in 12 days and B in 18 days. Together they can do it in:

• A. 6.2 days
• B. 7.2 days (Correct)
• C. 8 days
• D. 9 days

Explanation: Combined rate = 1/12 + 1/18 = 5/36, so time = 36/5 = 7.2 days.

2. If A does a work in 10 days, A's one-day work is:

• A. 1/5
• B. 1/10 (Correct)
• C. 1/12
• D. 1/15

Explanation: One-day work is reciprocal of total days = 1/10.

3. A pipe fills a tank in 6 hours and another empties it in 12 hours. If both are open, the tank fills in:

• A. 6
• B. 8
• C. 10
• D. 12 (Correct)

Explanation: Net rate = 1/6 - 1/12 = 1/12, so time = 12 hours.

4. If A is twice as efficient as B, then A:B working times are:

• A. 1:2 (Correct)
• B. 2:1
• C. 1:4
• D. 4:1

Explanation: Time is inversely proportional to efficiency.

5. If 5 men complete a work in 12 days, then 1 man will complete it in:

• A. 50 days
• B. 55 days
• C. 60 days (Correct)
• D. 65 days

Explanation: Total man-days = 5 × 12 = 60.

6. A completes a work in 10 days and B in 15 days. If they work on alternate days starting with A, the work finishes in:

• A. 11 days
• B. 12 days (Correct)
• C. 13 days
• D. 14 days

Explanation: In 2 days they do 1/10 + 1/15 = 1/6. In 10 days they do 5/6. Remaining 1/6 is done in 2 more days with A then B pattern, so 12 days.

7. Two pipes fill a tank in 20 and 30 minutes respectively. Together they fill it in:

• A. 10 min
• B. 12 min (Correct)
• C. 15 min
• D. 18 min

Explanation: Combined rate = 1/20 + 1/30 = 1/12.

8. A, B, and C can do a work in 12, 18, and 36 days respectively. Together they finish it in:

• A. 4 days
• B. 5 days
• C. 6 days (Correct)
• D. 7 days

Explanation: 1/12 + 1/18 + 1/36 = 3/36 + 2/36 + 1/36 = 6/36 = 1/6, so the work finishes in 6 days.

9. If A is thrice as efficient as B, then A can finish the work in 12 days and B in:

• A. 24
• B. 30
• C. 36 (Correct)
• D. 40

Explanation: If A is 3 times efficient, B takes 3 times the time = 36 days.

10. 15 workers can finish a work in 8 days. How many workers are needed to finish it in 6 days?

• A. 18
• B. 20 (Correct)
• C. 22
• D. 24

Explanation: Workers × days = constant, so 15 × 8 / 6 = 20.

11. A pipe fills a cistern in 4 hours and another in 6 hours. A waste pipe empties it in 12 hours. All three together fill it in:

• A. 2 hours
• B. 2.4 hours
• C. 3 hours (Correct)
• D. 3.5 hours

Explanation: Net rate = 1/4 + 1/6 - 1/12 = 5/12 - 1/12 = 4/12 = 1/3, so time is 3 hours.

12. If a man can do 1/20 of a work in a day, he will finish the whole work in:

• A. 10
• B. 15
• C. 20 (Correct)
• D. 25

Explanation: Total time is reciprocal of one-day work = 20 days.

13. A and B together do a work in 8 days. If A alone takes 24 days, B alone takes:

• A. 10
• B. 12 (Correct)
• C. 16
• D. 24

Explanation: 1/B = 1/8 - 1/24 = 2/24 = 1/12, so B takes 12 days.

14. A can do a work in 20 days. After working 5 days, B joins and they finish the remaining work in 5 days. B alone can do the work in:

• A. 10 (Correct)
• B. 15
• C. 20
• D. 25

Explanation: A does 5/20 = 1/4 in 5 days, remaining = 3/4. A+B do 3/4 in 5 days, so rate = 3/20. B = 3/20 - 1/20 = 1/10, so B takes 10 days.

15. 12 men or 18 women can complete a work in 10 days. Ratio of efficiency of a man to a woman is:

• A. 2:3
• B. 3:2 (Correct)
• C. 3:5
• D. 5:3

Explanation: Since 12 men = 18 women, 1 man = 18/12 women = 3/2 women.