Time and Work


  1. Seventy-five men are employed to lay down a railway line in 3 months. Due to certain emergency conditions, the work was to be finished in 18 days. How many more men should be employed to complete the work in the desired time ?









  1. View Hint View Answer Discuss in Forum

    Using Rule 1,
    M1D1 = M2D2
    ⇒ 75 × 90 = M2 × 18

    ⇒ M2 =
    75 × 90
    = 375
    18

    7there4; Number of additional men
    = 375 – 75 = 300

    Correct Option: A

    Using Rule 1,
    M1D1 = M2D2
    ⇒ 75 × 90 = M2 × 18

    ⇒ M2 =
    75 × 90
    = 375
    18

    7there4; Number of additional men
    = 375 – 75 = 300


  1. If 4 men or 8 women can do a piece of work in 15 days, in how many days can 6 men and 12 women do the same piece of work ?











  1. View Hint View Answer Discuss in Forum

    4 men ≡ 8 women
    ⇒ 1 man ≡ 2 women
    ∴ 6 men + 12 women ≡ 12 women + 12 women ≡ 24 women
    ∴ M1D1 = M2D2
    ⇒ 8 × 15 = 24 × D2

    ⇒ D2 =
    8 × 15
    = 5 days
    24

    Aliter : Using Rule 12,
    Here, A = 4, B = 8, a = 15
    A1 = 6, B1= 12
    Required number of days
    =
    a(A × B)
    A1B + B1A

    =
    15 × 32
    = 5 days
    96

    Correct Option: E

    4 men ≡ 8 women
    ⇒ 1 man ≡ 2 women
    ∴ 6 men + 12 women ≡ 12 women + 12 women ≡ 24 women
    ∴ M1D1 = M2D2
    ⇒ 8 × 15 = 24 × D2

    ⇒ D2 =
    8 × 15
    = 5 days
    24

    Aliter : Using Rule 12,
    Here, A = 4, B = 8, a = 15
    A1 = 6, B1= 12
    Required number of days
    =
    a(A × B)
    A1B + B1A

    =
    15 × 32
    = 5 days
    96



  1. 24 men can do a piece of work in 17 days. How many men will be able to do it in 51 days ?









  1. View Hint View Answer Discuss in Forum

    M1D1 = M2D2
    ⇒ 24 × 17 = M2 × 51

    ⇒ M2 =
    24 × 17
    = 8 men
    51

    Correct Option: B

    M1D1 = M2D2
    ⇒ 24 × 17 = M2 × 51

    ⇒ M2 =
    24 × 17
    = 8 men
    51


  1. Suman can do a work in 3 days. Sumati can do the same work in 2 days. Both of them finish the work together and get ₹ 150. What is the share of Suman ?









  1. View Hint View Answer Discuss in Forum

    Ratio of Suman’s and Sumati’s 1 day’s work

    =
    1
    :
    1
    = 2 : 3
    32

    Sum of the ratios = 2 + 3 = 5
    Suman’s share =
    2
    × 150 = ₹ 60
    5

    Aliter : Using Rule 24,
    Here, m = 3, n = 2, R = 150
    Share of suman =
    n
    × R
    m + n

    =
    2
    × 150 = 60
    3 + 2

    Correct Option: B

    Ratio of Suman’s and Sumati’s 1 day’s work

    =
    1
    :
    1
    = 2 : 3
    32

    Sum of the ratios = 2 + 3 = 5
    Suman’s share =
    2
    × 150 = ₹ 60
    5

    Aliter : Using Rule 24,
    Here, m = 3, n = 2, R = 150
    Share of suman =
    n
    × R
    m + n

    =
    2
    × 150 = 60
    3 + 2



  1. The average wage of 500 workers was found to be ₹ 200. Later on, it was discovered that the wages of two workers were misread as 180 and 20 instead of 80 and 220. The correct average wage is :









  1. View Hint View Answer Discuss in Forum

    Total wages of 500 workers
    = 500 × 200 = ₹ 100000
    Now, according to question, Correct Average

    =
    100000 - 180 - 20 + 80 + 220
    500

    =
    100100
    = ₹ 200.20
    500

    Correct Option: B

    Total wages of 500 workers
    = 500 × 200 = ₹ 100000
    Now, according to question, Correct Average

    =
    100000 - 180 - 20 + 80 + 220
    500

    =
    100100
    = ₹ 200.20
    500