Number System


  1. A man engaged a servant on the condition that he would pay him ₹ 90 and a turban after service of one year. He served only for nine months and received the turban and an amount of ₹ 65. The price of turban is









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    12 months’ salary = ₹ 90 + turban
    ∴  9 months’ salary

    = (₹ 90 + turban) ×
    9
    12

    = ₹ 90 ×
    3
    +
    3
    turban
    44

    = ₹
    135
    +
    3
    turban
    24

    ∴  ₹
    135
    +
    3
    turban
    24

    = ₹ 65 + turban
    ∴ 
    1
    turban =
    135
    − 65 = ₹
    5
    422

    ∴  Turban ⇒
    5
    × 4 = ₹ 10
    2

    Correct Option: C

    12 months’ salary = ₹ 90 + turban
    ∴  9 months’ salary

    = (₹ 90 + turban) ×
    9
    12

    = ₹ 90 ×
    3
    +
    3
    turban
    44

    = ₹
    135
    +
    3
    turban
    24

    ∴  ₹
    135
    +
    3
    turban
    24

    = ₹ 65 + turban
    ∴ 
    1
    turban =
    135
    − 65 = ₹
    5
    422

    ∴  Turban ⇒
    5
    × 4 = ₹ 10
    2


  1. If the operation ‘ * ’ is defined by a * b = a + b – ab, then 5 * 7 equals









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    ∵  a * b = a + b – ab
    ∴  5 * 7 = 5 + 7 – 5 × 7 = 12 – 35
    = – 23

    Correct Option: C

    ∵  a * b = a + b – ab
    ∴  5 * 7 = 5 + 7 – 5 × 7 = 12 – 35
    = – 23



  1. A number is doubled and 9 is added. If the resultant is trebled, it becomes 75. What is that number ?









  1. View Hint View Answer Discuss in Forum

    Suppose number is x.
    ∴  3 (2x + 9) = 75
    ⇒  6x + 27 = 75
    ⇒  6x = 48 ⇒ x = 8

    Correct Option: C

    Suppose number is x.
    ∴  3 (2x + 9) = 75
    ⇒  6x + 27 = 75
    ⇒  6x = 48 ⇒ x = 8


  1. The sum of two number is 8 and their product is 15. The sum of their reciprocals is









  1. View Hint View Answer Discuss in Forum

    If the numbers be x and y,
    then
    x + y = 8 ....... (i)
    xy = 15 ...... (ii)
    Dividing equation (i) by (ii)

    x + y
    =
    8
    ⇒ 
    x
    +
    y
    =
    8
    xy15xyxy15

    1
    +
    1
    =
    8
    yx15

    Correct Option: A

    If the numbers be x and y,
    then
    x + y = 8 ....... (i)
    xy = 15 ...... (ii)
    Dividing equation (i) by (ii)

    x + y
    =
    8
    ⇒ 
    x
    +
    y
    =
    8
    xy15xyxy15

    1
    +
    1
    =
    8
    yx15



  1. In a division sum, the divisor is 12 times the quotient and 5 times the remainder. If the remainder is 36, then the dividend is









  1. View Hint View Answer Discuss in Forum

    Divisor = 5 × remainder
    = 5 × 36 = 180
    Again, Divisor = 12 × quotient
    ∴  180 = 12 × quotient

    ∴  Quotient =
    180
    = 15
    12

    ∴  Dividend = Divisor × Quotient + Remainder
    = 180 × 15 + 36
    = 2700 + 36 = 2736

    Correct Option: C

    Divisor = 5 × remainder
    = 5 × 36 = 180
    Again, Divisor = 12 × quotient
    ∴  180 = 12 × quotient

    ∴  Quotient =
    180
    = 15
    12

    ∴  Dividend = Divisor × Quotient + Remainder
    = 180 × 15 + 36
    = 2700 + 36 = 2736