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- Question
A and B can complete a work in 15 days and 10 days respectively. They started doing the work together but after 2 days B had to leave and A alone completed the remaining work. The whole work was completed in :
Options- A. 8 days
- B. 10 days
- C. 12 days
- D. 15 days
- Correct Answer
- 12 days
Explanation(A + B)'s 1 day's work = ❨ 1 + 1 ❩ = 1 . 15 10 6 Work done by A and B in 2 days = ❨ 1 x 2 ❩ = 1 . 6 3 Remaining work = ❨ 1 - 1 ❩ = 2 . 3 3 Now, 1 work is done by A in 1 day. 15 ∴ 2 work will be done by a in ❨ 15 x 2 ❩ = 10 days. 3 3 Hence, the total time taken = (10 + 2) = 12 days.
More questions
- 1. In a race of 600 m, A can beat B by 60 m and in a race of 500 m, B can beat C by 50 m. By how many meters will A beat C in a race of 400 m?
Options- A. 364 m
- B. 254 m
- C. 324 m
- D. 354 m Discuss
Correct Answer: 324 m
Explanation:
Clearly, if A runs 600 meters, B runs = 540 m.
? If A runs 400 m, B runs = 540 x 400 / 600 = 540 x 4 / 6 = 90 x 4 = 360 m
Again, when B runs 500 m, C runs = 450 m
? When B runs 360 m, C runs = 450 x 360 / 500 = 45 x 36 / 5 = 9 x 36 = 324 m.
? A beats C by 400 - 324 = 76 m.- 2. 36.98276421 x 21.00002 =?
Options- A. 775
- B. 785
- C. 800
- D. 805 Discuss
Correct Answer: 775
Explanation:
36.98276421 x 21.00002
Using nearest value in whole number for 36.9827421 is 37 and 21.0002 is 21
? 37 x 21 = 777 ? 775- 3. In the figure, BD and CD are angle bisectors of ? ABC and ? ACE, respectively. Then ? BDC is equal to :
Options- A. ?BAC
- B. 2?BAC
- C. 1 ?BAC 2
- D. 1 ?BAC 3 Discuss
Correct Answer: 1 ?BAC 2
Explanation:
- 4. What is the unit digit in {(6374)1793 x (625)317 x (341491)}?
Options- A. 0
- B. 2
- C. 3
- D. 5 Discuss
Correct Answer: 0
Explanation:
Unit digit in (6374) 1793 = Unit digit in (4) 1793= Unit digit in [(42)896 x 4]
= Unit digit in (6 x 4) = 4
Unit digit in (625)317 = Unit digit in (5)317 = 5
Unit digit in (341)491 = Unit digit in (1)491 = 1
Required digit = Unit digit in (4 x 5 x 1) = 0.
- 5. How many seconds will a 500 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?
Options- A. 25
- B. 30
- C. 40
- D. 45 Discuss
Correct Answer: 30
Explanation:
Speed of the train relative to man = (63 - 3) km/hr = 60 km/hr = ❨ 60 x 5 ❩ m/sec 18 = ❨ 50 ❩ m/sec. 3 ∴ Time taken to pass the man = ❨ 500 x 3 ❩ sec 50 = 30 sec. - 6. Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:
Options- A. 2 : 3
- B. 4 : 3
- C. 6 : 7
- D. 9 : 16 Discuss
Correct Answer: 4 : 3
Explanation:
Let us name the trains as A and B. Then,(A's speed) : (B's speed) = √b : √a = √16 : √9 = 4 : 3.
- 7. A train travelling at a speed of 75 mph enters a tunnel 3½ miles long. The train is ¼ mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?
Options- A. 2.5 min
- B. 3 min
- C. 3.2 min
- D. 3.5 min Discuss
Correct Answer: 3 min
Explanation:
Total distance covered = ❨ 7 + 1 ❩ miles 2 4 = 15 miles. 4 ∴ Time taken = ❨ 15 ❩ hrs 4 x 75 = 1 hrs 20 = ❨ 1 x 60 ❩ min. 20 = 3 min. - 8. Which one of the following numbers is completely divisible by 45?
Options- A. 181560
- B. 331145
- C. 202860
- D. 2033555
- E. None of these Discuss
Correct Answer: 202860
Explanation:
45 = 5 x 9, where 5 and 9 are co-primes.Unit digit must be 0 or 5 and sum of digits must be divisible by 9.
Among given numbers, such number is 202860.
- 9. 7589 -? = 3434
Options- A. 4242
- B. 4155
- C. 1123
- D. 11023
- E. None of these Discuss
Correct Answer: 4155
Explanation:
Let 7589 -x = 3434Then, x = 7589 - 3434 = 4155
- 10. Find the angle between minute hand hour hand at 11 : 50 AM
Options- A. 55°
- B. 22.5°
- C. 15°
- D. None of these Discuss
Correct Answer: 55°
Explanation:
At 11 : 50 A.M. from the formula here P = 11 and Q = 50 so required angle is 11 x 50/2 - 30 x 11 = 275 - 330 = -55 or ignoring the negative sign the required angle is 55°
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