NextMockSearch exams, e.g. SSC CGL, UPPSC, Lekhpal
Railways PYQCBT 1 2016

RRB NTPC · Question 34

X does 25% of a work in 20 days. Y joins X and they together finish the remaining work in 15 days. Y alone can do the whole work in _____ days. A. 30 days B. \(25\frac{1}{2}\) days C. \(26\frac{2}{3}\) days D. \(26\frac{1}{3}\) days

  1. A

  2. D

  3. B

  4. C

Show answer & explanation

Answer: (D) C

Explanation

X does 25% in 20 days, so X alone needs 80 days. X and Y finish the remaining 75% in 15 days, i.e. together they do 3/4 ÷ 15 = 1/20 per day. Y's rate = 1/20 − 1/80 = 3/80, so Y alone takes 80/3 = 26⅔ days.