12 men take 6 days to complete a piece of work. They

Solution

12 men = 6 days Work done by 12 men in one day = 1/6  Work done by 12 men in 2 days = 1/6 × 2 = 1/3  Remaining work = 1 - 1/3 = 2/3 Now, 4 men joined them Therefore, 2/3 rd of work is done by 16 men in x days We have the formula, M1 × D1 / W1 = M2 × D2 / W2 Here, M1 = 12, D1 = 2 and W1 = 1/3 M2 = 16, D2 = x and W2 = 2/3  (12  ×  2)/(1/3) = (16 ×  x  )/(2/3  ) x = 3 days  ALTERNATE SHORTCUT METHOD M1 × D1 = M2 × D2  12× 6 = 12× 2 +(12+4) × x 72 = 24 +16 x 48 = 16 x So x=3days