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- Question
Two pipes A and B can fill a tank in 20 and 30 minutes respectively. If both the pipes are used together, then how long will it take to fill the tank?
Options- A. 12 min
- B. 15 min
- C. 25 min
- D. 50 min
- Correct Answer
- 12 min
ExplanationPart filled by A in 1 min = 1 . 20 Part filled by B in 1 min = 1 . 30 Part filled by (A + B) in 1 min = ❨ 1 + 1 ❩ = 1 . 20 30 12 ∴ Both pipes can fill the tank in 12 minutes.
More questions
- 1. A train 300 meters long passes a standing man is 15 seconds. The speed of the train is?
Options- A. 40 km/hr
- B. 50 km/hr
- C. 60 km/hr
- D. 72 km/hr Discuss
Correct Answer: 72 km/hr
Explanation:
? Speed = Distance / Time = (300/15)
= 20 m/sec
= (20 x 18) / 5 = 72 km/hr- 2. If the diagonal of a square is double, how does the area of the square change?
Options- A. Becomes four fold
- B. Becomes three fold
- C. Becomes two fold
- D. None of the above Discuss
Correct Answer: Becomes four fold
Explanation:
Ratio of the areas = area of original square / area of new square
= [ d2 / 2 ] / [ (2d)2 / 2 ] = 1/4
? New area becomes 4 fold.- 3. 46080, 3840, 384, 48, 24, 2, 1
Options- A. 1
- B. 2
- C. 24
- D. 384 Discuss
Correct Answer: 24
Explanation:
The terms are successively divided by 12, 10, 8, 6, ...etc.So, 24 is wrong, it should be 8 (48/6 = 8).
- 4. The difference between the length and breadth of a rectangle is 23 m. If its perimeter is 206 m, then its area is:
Options- A. 1520 m2
- B. 2420 m2
- C. 2480 m2
- D. 2520 m2 Discuss
Correct Answer: 2520 m2
Explanation:
We have: (l - b) = 23 and 2(l + b) = 206 or (l + b) = 103.Solving the two equations, we get: l = 63 and b = 40.
∴ Area = (l x b) = (63 x 40) m2 = 2520 m2.
- 5. 4/5 of a number exceeds its 2/3 by 8. The number is?
Options- A. 30
- B. 60
- C. 90
- D. None of these Discuss
Correct Answer: 60
Explanation:
Let the number be x,
Then, 4x/5 - 2x/3 = 8
? (12x - 10x) / 15 = 8
? 2x = 120
? x = 60- 6. Find the angle between minute hand and hour hand at 2 : 18 AM
Options- A. 37°
- B. 33°
- C. 39°
- D. None of these Discuss
Correct Answer: 39°
Explanation:
39°
- 7. Rakesh, Dinesh and Mahesh start a business by investing ? 5000 , ? 8000 and ? 12000 , respectively . At the end of year, they got the profit of ? 12500. What is the share of Dinesh in profit?
Options- A. ? 4000
- B. ? 4500
- C. ? 6000
- D. ? 7500 Discuss
Correct Answer: ? 4000
Explanation:
Share of Rakesh : Share of Dinesh : Share of Mahesh
= 5000 : 8000 : 12000 = 5 : 8 : 12
Total earned profit = ? 12500
? Share of Dinesh in profit
= [8/(5 + 8 + 12)] x 12500 = (8/25) x 12500
= 8 x 500 = ? 4000- 8. The least multiple of 7, which leaves a remainder of 4, when divided by 6, 9, 15 and 18 is:
Options- A. 74
- B. 94
- C. 184
- D. 364 Discuss
Correct Answer: 364
Explanation:
L.C.M. of 6, 9, 15 and 18 is 90.Let required number be 90k + 4, which is multiple of 7.
Least value of k for which (90k + 4) is divisible by 7 is k = 4.
∴ Required number = (90 x 4) + 4 = 364.
- 9. If log 27 = 1.431, then the value of log 9 is:
Options- A. 0.934
- B. 0.945
- C. 0.954
- D. 0.958 Discuss
Correct Answer: 0.954
Explanation:
log 27 = 1.431⟹ log (33 ) = 1.431
⟹ 3 log 3 = 1.431
⟹ log 3 = 0.477
∴ log 9 = log(32 ) = 2 log 3 = (2 x 0.477) = 0.954.
- 10. A box contains 2 white balls, 3 black balls and 4 red balls. In how many ways can 3 balls be drawn from the box, if at least one black ball is to be included in the draw?
Options- A. 32
- B. 48
- C. 64
- D. 96
- E. None of these Discuss
Correct Answer: 64
Explanation:
We may have(1 black and 2 non-black) or (2 black and 1 non-black) or (3 black).∴ Required number of ways = (3C1 x 6C2) + (3C2 x 6C1) + (3C3) = ❨ 3 x 6 x 5 ❩ + ❨ 3 x 2 x 6 ❩ + 1 2 x 1 2 x 1 = (45 + 18 + 1) = 64.
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