GATE Practice Question and Answer

Q: In a group of 6 boys and 4 girls, four children are to be selected. In how many different ways can they be selected such that at least one boy should be there ? 1927 0

  • 1
    205
    Correct
    Wrong
  • 2
    194
    Correct
    Wrong
  • 3
    209
    Correct
    Wrong
  • 4
    159
    Correct
    Wrong
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Answer : 3. "209"
Explanation :

Answer: C) 209 Explanation: We may have (1 boy and 3 girls)or(2boys and 2 girls)or(3 boys and 1 girl)or(4 boys). Required number of ways = (C16× C34) + C26×C24  + (C36× C14) + (C46)   = (24+90+80+15)  = 209.

Q: Which has the lowest albedo? 1926 0

  • 1
    dark surfaces
    Correct
    Wrong
  • 2
    light surfaces
    Correct
    Wrong
  • 3
    Both A & B
    Correct
    Wrong
  • 4
    None of the above
    Correct
    Wrong
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Answer : 1. "dark surfaces"
Explanation :

Answer: A) dark surfaces Explanation: Albedo refers to a material's ability to reflect sunlight. Since 30% of the sun's energy is reflected by the entire earth, the earth has an average albedo of 0.30. Generally, dark surfaces have a low albedo and light surfaces have a high albedo.

Q: A letter lock consists of three rings each marked with six different letters. The number of distinct unsuccessful attempts to open the lock is at the most  ? 1926 0

  • 1
    215
    Correct
    Wrong
  • 2
    268
    Correct
    Wrong
  • 3
    254
    Correct
    Wrong
  • 4
    216
    Correct
    Wrong
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Answer : 1. "215"
Explanation :

Answer: A) 215 Explanation: Since each ring consists of six different letters, the total number of attempts possible with the three rings is = 6 x 6 x 6 = 216. Of these attempts, one of them is a successful attempt.   Maximum number of unsuccessful attempts = 216 - 1 = 215.

Q: Kalyan purchased a Maruti van for Rs. 1,96,000 and the rate of depreciation is 14(2/7) % per annum. Find the value of the van after two years ? 1925 0

  • 1
    Rs. 1,24,000
    Correct
    Wrong
  • 2
    Rs. 1,44,000
    Correct
    Wrong
  • 3
    Rs. 1,32,000
    Correct
    Wrong
  • 4
    Rs. 1,62,000
    Correct
    Wrong
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Answer : 2. "Rs. 1,44,000"
Explanation :

Answer: B) Rs. 1,44,000 Explanation: Value of Maruti Van, V1 = Rs. 1,96,000Rate of depreciation, r = 14(2/7)% = 100/7%; Time, t = 2 yearsLet V2 is the value after depreciation. V2 = V11 - r100tV2 = 196001 - 10071002 V2 = 196000(6/7)(6/7) V2 = (196000x36)/49 = Rs. 1,44,000.

Q: 20 men went to a restaurant. Ninteen of them paid Rs.70 each and the twentieth man paid Rs.90.25 more than the average of all the 20 men. What is the total bill ? 1924 0

  • 1
    Rs. 1495
    Correct
    Wrong
  • 2
    Rs. 548
    Correct
    Wrong
  • 3
    Rs. 850
    Correct
    Wrong
  • 4
    Rs. 1750
    Correct
    Wrong
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Answer : 1. "Rs. 1495"
Explanation :

Answer: A) Rs. 1495 Explanation: Let the average bill paid by twenty members = 'x' But 19 men paid each = Rs. 70 20th man paid Rs. 90.25 more than the avg bill of 20 = x + 90.25 20x = 19(70) + x + 90.2519x = 1330 + 90.2519x = 1420.25x = 1420.25/19 = Rs. 74.75 But the total bill = 20 x 74.75 = Rs. 1495.

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Answer : 1. "87"
Explanation :

Answer: A) 87 Explanation: Cp1 = p2 - p1 , Cp2 = p3 - p2 ......Cp23 = p24 - p23Sum of series = (p2-p1) + (p3-p2) + .....(p23-p22) + (p24-p23)All terms get cancelled, except p1 = 2 and p24 = 89 So Sum = -p1 + p24Sum of series = -2 + 89 = 87

Q: What is the science of mapmaking called? 1921 0

  • 1
    Coriography
    Correct
    Wrong
  • 2
    Cartography
    Correct
    Wrong
  • 3
    Photograrnmetry
    Correct
    Wrong
  • 4
    Mapping
    Correct
    Wrong
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Answer : 2. "Cartography"
Explanation :

Answer: B) Cartography Explanation: The art and science of map making is called Cartography.

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