Numerical Ability


  1. What will be the maximum sum of 44, 42, 40, ........, 2, 0?
    1. 502
    2. 504
    3. 506
    4. 500

  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. What will be the maximum sum of 44, 42, 40, ........, 2, 0?
    1. 502
    2. 504
    3. 506
    4. 500

  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
    1. P, Q
    2. Q, R
    3. P, R
    4. R, S

  1. View Hint View Answer Discuss in Forum

    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
    1. 0.288
    2. 0.334
    3. 0.667
    4. 0.720

  1. View Hint View Answer Discuss in Forum


    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
    1. 8 meters
    2. 10 meters
    3. 12 meters
    4. 14 meters

  1. View Hint View Answer Discuss in Forum

    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