GATE Practice Question and Answer

Q: Pipe A can fill a tank in 16 minutes and pipe B cam empty it in 24 minutes. If both the pipes are opened together after how many minutes should pipe B be closed, so that the tank is filled in 30 minutes  ? 3149 0

  • 1
    21 min
    Correct
    Wrong
  • 2
    24 min
    Correct
    Wrong
  • 3
    20 min
    Correct
    Wrong
  • 4
    22 min
    Correct
    Wrong
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Answer : 1. "21 min"
Explanation :

Answer: A) 21 min Explanation: Let the pipe B be closed after 'K' minutes. 30/16 - K/24 = 1 => K/24 = 30/16 - 1 = 14/16 => K = 14/16 x 24 = 21 min.

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Answer : 2. "30 min"
Explanation :

Answer: B) 30 min Explanation: Distance travelled by Ramu = 45 x 4 = 180 km Somu travelled the same distance in 6 hours. His speed = 180/6 = 30 km/hr Hence in the conditional case, Ramu's speed = 45 - 9 = 36 km/hr and Somu's speed = 30 + 10 = 40km/hr. Therefore travel time of Ramu and Somu would be 5 hours and 4.5 hours respectively. Hence difference in the time taken = 0.5 hours = 30 minutes.

Q: 217 x 217 + 183 x 183 = ? 1123 0

  • 1
    84521
    Correct
    Wrong
  • 2
    87487
    Correct
    Wrong
  • 3
    80578
    Correct
    Wrong
  • 4
    78458
    Correct
    Wrong
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Answer : 3. "80578"
Explanation :

Answer: C) 80578 Explanation: 2172+1832   = 200+172+200-172   It is in the form of a+b2+a-b2=2a2+b2   = 2(40000 + 289) = 80578.

Q: The incomes of two persons A and B are in the ratio 3:4. If each saves Rs.100 per month, the ratio of their expenditures is 1:2. Find their incomes  ? 4633 0

  • 1
    200, 400
    Correct
    Wrong
  • 2
    100, 300
    Correct
    Wrong
  • 3
    100, 200
    Correct
    Wrong
  • 4
    150, 200
    Correct
    Wrong
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Answer : 4. "150, 200"
Explanation :

Answer: D) 150, 200 Explanation: The incomes of A and B be 3P and 4P. Expenditures = Income - Savings (3P - 100) and (4P - 100) The ratio of their expenditure = 1:2 (3P - 100):(4P - 100) = 1:2 2P = 100 => P = 50 Their incomes = 150, 200

Q: Two trains of equal length, running with the speeds of 60 and 40 kmph, take 50 seconds to cross each other while they are running in the same direction. What time will they take to cross each other if they are running in opposite directions  ? 3875 0

  • 1
    10 sec
    Correct
    Wrong
  • 2
    11 sec
    Correct
    Wrong
  • 3
    12 sec
    Correct
    Wrong
  • 4
    8 sec
    Correct
    Wrong
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Answer : 1. "10 sec"
Explanation :

Answer: A) 10 sec Explanation: Relative Speed = 60 -40 = 20 x 5/18 = 100/18 Time = 50 Distance = 50 x 100/18 = 2500/9 Relative Speed = 60 + 40 = 100 x 5/18 Time = 2500/9 x 18/500 = 10 sec.

Q: 3 men, 4 women and 6 children can complete a work in 7 days. A woman does double the work a man does and a child does half the work a man does. How many women alone can complete this work in 7 days  ? 5764 0

  • 1
    6
    Correct
    Wrong
  • 2
    9
    Correct
    Wrong
  • 3
    5
    Correct
    Wrong
  • 4
    7
    Correct
    Wrong
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Answer : 4. "7"
Explanation :

Answer: D) 7 Explanation: Let 1 woman's 1 day work = x. Then, 1 man's 1 day work = x/2 and 1 child's 1 day work  x/4. So, (3x/2 + 4x + + 6x/4) = 1/7 28x/4 = 1/7 => x = 1/49 1 woman alone can complete the work in 49 days. So, to complete the work in 7 days, number of women required = 49/7 = 7.

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Answer : 3. "8.57 min"
Explanation :

Answer: C) 8.57 min Explanation: 1/10 + 1/15 = 1/6 x 3 = 1/2 1 - 1/2 = 1/2 1/10 + 1/15 - 1/x = 1/2 x = 8.57 min

Q: Two persons start running simultaneously around a circular track of length 300 m from the same point at speeds of 15 km/hr and 25 km/hr. When will they meet for the first time any where on the track if they are moving in opposite directions  ? 5114 0

  • 1
    27 sec
    Correct
    Wrong
  • 2
    31 sec
    Correct
    Wrong
  • 3
    23 sec
    Correct
    Wrong
  • 4
    29 sec
    Correct
    Wrong
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Answer : 1. "27 sec"
Explanation :

Answer: A) 27 sec Explanation: Time taken to meet for the first time anywhere on the track = length of the track / relative speed = 300 / (15 + 25)5/18 = 300x 18 / 40 x 5 = 27 seconds.

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