Numerical Ability


  1. What will be the maximum sum of 44, 42, 40, ........, 2, 0?









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    Sn =
    n
    [ 2a + (n - 1)d ]
    2

    44, 42, 40, ------ 2, 0
    Here , a = 44 , d = -2 , n = 22 terms
    S22 =
    22
    [ 2 × 44 + (22 - 1)(-2) ]
    2

    S22 =
    22
    [ 88 - 42 ]
    2

    S22 =
    22
    × [ 46 ]
    2

    S22 = 11 × 46 = 506

    Correct Option: C

    Sn =
    n
    [ 2a + (n - 1)d ]
    2

    44, 42, 40, ------ 2, 0
    Here , a = 44 , d = -2 , n = 22 terms
    S22 =
    22
    [ 2 × 44 + (22 - 1)(-2) ]
    2

    S22 =
    22
    [ 88 - 42 ]
    2

    S22 =
    22
    × [ 46 ]
    2

    S22 = 11 × 46 = 506


  1. What will be the maximum sum of 44, 42, 40, ........, 2, 0?









  1. View Hint View Answer Discuss in Forum

    Sn =
    n
    [ 2a + (n - 1)d ]
    2

    44, 42, 40, ------ 2, 0
    Here , a = 44 , d = -2 , n = 22 terms
    S22 =
    22
    [ 2 × 44 + (22 - 1)(-2) ]
    2

    S22 =
    22
    [ 88 - 42 ]
    2

    S22 =
    22
    × [ 46 ]
    2

    S22 = 11 × 46 = 506

    Correct Option: C

    Sn =
    n
    [ 2a + (n - 1)d ]
    2

    44, 42, 40, ------ 2, 0
    Here , a = 44 , d = -2 , n = 22 terms
    S22 =
    22
    [ 2 × 44 + (22 - 1)(-2) ]
    2

    S22 =
    22
    [ 88 - 42 ]
    2

    S22 =
    22
    × [ 46 ]
    2

    S22 = 11 × 46 = 506



  1. Which of the following assertions are CORRECT?
    P : Adding 7 to each entry in a list adds 7 to the mean of the list
    Q : Adding 7 to each entry in a list adds 7 to the standard deviation of the list
    R : Doubling each entry in a list doubles the mean of the list
    S : Doubling each entry in a list leaves the standard deviation of the list unchanged









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    P and R always holds true
    Else consider a sample set {1, 2, 3, 4} and check accordingly.

    Correct Option: C

    P and R always holds true
    Else consider a sample set {1, 2, 3, 4} and check accordingly.


  1. An automobile plant contracted to buy shock absorbers from two suppliers X and Y. X supplies 60% and V supplies 40% of the shock absorbers. All shock absorbers are subjected to a quality test. The ones that pass the quality test are considered reliable. Of X's shock absorbers, 96% are reliable. Of Y's shock absorbers, 72% are reliable. The probability that a randomly chosen shock absorber, which is found to be reliable, is made by Y is









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    XY
    Supply60%40%
    Reliable96%72%
    Overall0.5760.228


    ∴ P(X) =
    0.288
    = 0.334
    0.576 + 0.288

    Correct Option: B


    XY
    Supply60%40%
    Reliable96%72%
    Overall0.5760.228


    ∴ P(X) =
    0.288
    = 0.334
    0.576 + 0.288



  1. A political party orders an arch for the entrance to the ground in which the annual conventions is being held. The profile of the arch follows the equation y = 2x – 0.1x2 where y is the height of the arch in meters. The maximum possible height of the arch is









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    y = 2x – 0.1x2

    dy
    = 2 – 0.2x
    dx

    d2y
    < 0
    dx2

    Hence maximises at 2 – 0.2x = 0
    ⇒ x = 10
    ∴ y = 20 – 10 = 10 m

    Correct Option: B

    y = 2x – 0.1x2

    dy
    = 2 – 0.2x
    dx

    d2y
    < 0
    dx2

    Hence maximises at 2 – 0.2x = 0
    ⇒ x = 10
    ∴ y = 20 – 10 = 10 m