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Railways PYQCBT 2 2017

RRB NTPC · Question 86

'K' can do 3/4^thof a work in 6 days and 'J' can do 2/5^thof the same work in 4 days. How long (in days) will they take, if they together to finish the work?

  1. \(4 \frac{2}{3}\)

  2. \(4 \frac{3}{8}\)

  3. \(4 \frac{1}{4}\)

  4. \(4 \frac{4}{9}\)

Show answer & explanation

Answer: (D) \(4 \frac{4}{9}\)

Explanation

K does the whole work in 6 × 4/3 = 8 days; J in 4 × 5/2 = 10 days. Together: 1/8 + 1/10 = 9/40 per day, so 40/9 = 4 4/9 days.