GATE Practice Question and Answer

Q: A box contains 4 different black balls, 3 different red balls and 5 different blue balls. In how many ways can the balls be selected if every selection must have at least 1 black ball and one red ball ? 2815 0

  • 1
    24 - 1
    Correct
    Wrong
  • 2
    2425-1
    Correct
    Wrong
  • 3
    (24-1)(23-1)25
    Correct
    Wrong
  • 4
    None
    Correct
    Wrong
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Answer : 3. "(24-1)(23-1)25"
Explanation :

Answer: C) C Explanation: It is explicitly given that all the 4 black balls are different, all the 3 red balls are different and all the 5 blue balls are different. Hence this is a case where all are distinct objects.   Initially let's find out the number of ways in which we can select the black balls. Note that at least 1 black ball must be included in each selection.   Hence, we can select 1 black ball from 4 black ballsor 2 black balls from 4 black balls.or 3 black balls from 4 black balls.or 4 black balls from 4 black balls.   Hence, number of ways in which we can select the black balls   = 4C1 + 4C2 + 4C3 + 4C4= 24-1 ........(A)   Now let's find out the number of ways in which we can select the red balls. Note that at least 1 red ball must be included in each selection.   Hence, we can select 1 red ball from 3 red ballsor 2 red balls from 3 red ballsor 3 red balls from 3 red balls   Hence, number of ways in which we can select the red balls= 3C1 + 3C2 + 3C3=23-1........(B)   Hence, we can select 0 blue ball from 5 blue balls (i.e, do not select any blue ball. In this case, only black and red balls will be there)or 1 blue ball from 5 blue ballsor 2 blue balls from 5 blue ballsor 3 blue balls from 5 blue ballsor 4 blue balls from 5 blue ballsor 5 blue balls from 5 blue balls.   Hence, number of ways in which we can select the blue balls= 5C0 + 5C1 + 5C2 + … + 5C5= 25..............(C)   From (A), (B) and (C), required number of ways=  2524-123-1

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Answer : 3. "K & L"
Explanation :

Answer: C) K & L Explanation: Monday          - N  - Yellow Tuesday         - L  - White Wednesday    - O  - Red Thursday       - Q  - Orange Friday           - M  - Blue Saturday       - P  - Grey Sunday         - K  - Black From the above table, K & L visits Sunday & Tuesday and their favourite colors are Black and white respectively.

Q: Malleability and Ductility of metals can be accounted due to 2809 0

  • 1
    the crystalline structure in metal
    Correct
    Wrong
  • 2
    the interaction of electrons with metal ions in the lattice
    Correct
    Wrong
  • 3
    the presence of electrostatic force
    Correct
    Wrong
  • 4
    the capacity of layers of metal ions to slide over the other
    Correct
    Wrong
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Answer : 4. "the capacity of layers of metal ions to slide over the other"
Explanation :

Answer: D) the capacity of layers of metal ions to slide over the other Explanation:

Q: The last two digits of 2151415? 2808 0

  • 1
    81
    Correct
    Wrong
  • 2
    61
    Correct
    Wrong
  • 3
    91
    Correct
    Wrong
  • 4
    51
    Correct
    Wrong
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Answer : 4. "51"
Explanation :

Answer: D) 51 Explanation: Unit digit of this expression is always 1 as the base ends with 1.  For the tenth place digit we need to multiply the digit in the tenth place of the base and unit digit of the power and take its unit digit. i.e, tenth place digit in 2151 is 5 and tenth place digit in power 415 is 1 And the units digit in the product of 5 x 1 = 5   Therefore, last two digits of 2151415 is 51.

Q: What is the term used in tennis when the score is 40-40? 2807 0

  • 1
    Ace
    Correct
    Wrong
  • 2
    Led
    Correct
    Wrong
  • 3
    Deuce
    Correct
    Wrong
  • 4
    Tie
    Correct
    Wrong
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Answer : 3. "Deuce"
Explanation :

Answer: C) Deuce Explanation: When both sides have won the same number of points then: when each side has won one, or two, points, the score is described as "15-all" and "30-all" (or "15-up" and "30-up"), respectively. However, if each player has won three points, the score is called as "deuce", not "40–all". From that point on in the game, whenever the score is tied, it is described as "deuce", regardless of how many points have been played.

Q: Which number replaces the '?' in the given series 108, 127, 2413, 2430, 41310, ?, 619875 2806 0

  • 1
    41975
    Correct
    Wrong
  • 2
    41325
    Correct
    Wrong
  • 3
    84375
    Correct
    Wrong
  • 4
    41365
    Correct
    Wrong
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Answer : 2. "41325"
Explanation :

Answer: B) 41325 Explanation: The given series follows a pattern of +19, x19, +17, x17, +15, x15,... Here the number which is to be replaced in ? is 41310+15=41325.

Q: Planet : Orbit :: Projectile : ? 2801 0

  • 1
    Path
    Correct
    Wrong
  • 2
    Milky way
    Correct
    Wrong
  • 3
    Track
    Correct
    Wrong
  • 4
    Trajectory
    Correct
    Wrong
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Answer : 4. "Trajectory"
Explanation :

Answer: D) Trajectory Explanation: The path traced by planet is called Orbit. Similarly, the path traced by projectile is called Trajectory.   Hence, Planet : Orbit : : Projectile : Trajectory.

Q: Find the Odd One Out? 4, 6, 12, 30, 81, 315. 2801 0

  • 1
    6
    Correct
    Wrong
  • 2
    12
    Correct
    Wrong
  • 3
    81
    Correct
    Wrong
  • 4
    315
    Correct
    Wrong
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Answer : 3. "81"
Explanation :

Answer: C) 81 Explanation: Given the number series is 4, 6, 12, 30, 81, 315. Here it follows a pattern that 4 4 x 1.5 = 6 6 x 2 = 12 12 x 2.5 = 30 30 x 3 = 90 not equals to 81 90 x 3.5 = 315   Hence the odd one in the series is 81.

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