IIT JEE Practice Question and Answer

Q: If in the following set of numbers, the first and the third digits are interchanged in each number, which number will be second from the end if arranged in ascending order after interchanging the digits ? 585  546  514  404  206  369 1503 0

  • 1
    404
    Correct
    Wrong
  • 2
    585
    Correct
    Wrong
  • 3
    415
    Correct
    Wrong
  • 4
    602
    Correct
    Wrong
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Answer : 3. "415"
Explanation :

Answer: C) 415 Explanation: Given numbers are 585 546 514 404 206 369Then interchanging the 1st and 3rd digits of the given numbers, we get585 645 415 404 602 963Now, arranging them in ascending order963 645 602 585 415 404Then the last second number is 415.

Q: A Tank is normally filled in 9 hours but takes four hours longer to fill because of a leak in its bottom. If the tank is full, the leak will empty it in ? 1502 0

  • 1
    32.5 hrs
    Correct
    Wrong
  • 2
    29.25 hrs
    Correct
    Wrong
  • 3
    30.30 hrs
    Correct
    Wrong
  • 4
    31 hrs
    Correct
    Wrong
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Answer : 2. "29.25 hrs"
Explanation :

Answer: B) 29.25 hrs Explanation: Let the leak will empty the tank in x hrs  Then, 1/9 - 1/x = 1/13 x = 29.25 hrs

Q: The sum of the two digits of a number is 8. If the number is subtracted from the number obtained by reversing its digits, the result is 54. Find the number ? 1502 0

  • 1
    28
    Correct
    Wrong
  • 2
    19
    Correct
    Wrong
  • 3
    37
    Correct
    Wrong
  • 4
    17
    Correct
    Wrong
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Answer : 4. "17"
Explanation :

Answer: D) 17 Explanation: Any two digit number can be written as (10P + Q), where P is the digit in the tens place and Q is the digit in the units place.P + Q = 8 ----- (1)(10Q + P) - (10P + Q) = 549(Q - P) = 54(Q - P) = 6 ----- (2)Solve (1) and (2) P = 1 and Q = 7The required number is = 17

Q: Which of the following country has re-elected as the member of the UNESCO's executive board? 1502 0

  • 1
    Pakistan
    Correct
    Wrong
  • 2
    India
    Correct
    Wrong
  • 3
    Myanmar
    Correct
    Wrong
  • 4
    Nepal
    Correct
    Wrong
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Answer : 2. "India"
Explanation :

Answer: B) India Explanation: India was re-elected as member of executive board of United Nations Educational, Scientific and Cultural Organization (UNESCO). Executive board is UNESCO's top decision-making body. The election was held at 39th session of General Conference of UNESCO in Paris, France.    UNESCO is UN association that helps safeguard historical and cultural sites around the world. It is special multi-nation organization, framed in 1945 and situated in France. It promotes literacy and sex education as well as improving gender equality in countries around world. The General Conference determines policies and main lines of work of organisation. Its duty is to set programmes and budget of UNESCO. It also elects members of executive board and appoints, every four years, director-general.

Q: Which of these is a starting point for primary succession? 1500 0

  • 1
    a neglected yard
    Correct
    Wrong
  • 2
    a surface exposed by a retreating glacier
    Correct
    Wrong
  • 3
    an abandoned city
    Correct
    Wrong
  • 4
    abandoned farmland
    Correct
    Wrong
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Answer : 2. "a surface exposed by a retreating glacier"
Explanation :

Answer: B) a surface exposed by a retreating glacier Explanation:

Q: Why are manhole covers round? 1500 0

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Answer :
Explanation :

A number of possible explanations for why manhole covers are round include :   1. A round manhole cover cannot fall through its circular opening, whereas a square, rectangular, or oval manhole cover could fall in if it were inserted diagonally in the hole. 2. Circular covers don’t need to be rotated or precisely aligned when placing them on the opening. 3. A round manhole cover is easily moved and rolled. 4. Human beings have a roughly circular cross-section. 5. Round tubes are the strongest shape against the compression of the earth around them, so the cover of the tube would naturally be round as well. 6. It’s easier to dig a circular hole.

Q: The price of a car is increased by 25%, by how much percent, must the new price of this car be decreased to restore its original price ? 1499 0

  • 1
    20%
    Correct
    Wrong
  • 2
    24%
    Correct
    Wrong
  • 3
    21%
    Correct
    Wrong
  • 4
    25%
    Correct
    Wrong
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Answer : 1. "20%"
Explanation :

Answer: A) 20% Explanation: Suppose that the original price of the car = Rs. x  Then new price of the car => (x) + (x ×25/100) = Rs. 5x/4  To restore the original price, the new price must be decreased by 5x/4 − x = x/4 So required percentage =(x/4)/(5x/4) × 100% = 20%

Q: Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is  ? 1499 0

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

Answer: D) 3 : 2 Explanation: Let the speeds of the two trains be x m/sec and y m/sec respectively. Then, length of the first train = 27 x meters, and length of the second train = 17 y meters. (27 x + 17 y) / (x + y) = 23 => 27 x + 17 y = 23 x + 23 y => 4 x = 6 y => x/y = 3/2.

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