Time taken by A and B to complete a work is in the ratio 2 : 3. A alone worked for 5 days and left the work then B alone worked for 10 days on the same work, It is found than 70% of the work is completed. Find the time in which they together can complete the work.

Time taken by A and B to complete a work is in the ratio 2 : 3. A alone worked for 5 days and left the work then B alone worked for 10 days on the same work, It is found than 70% of the work is completed. Find the time in which they together can complete the work. Correct Answer 10 days

Ratio of time taken by A and B to complete a work = 2 ∶ 3

∴ Ratio of efficiency of A and B = 3 ∶ 2

Let, efficiency of A = 3x/day and efficiency of B = 2x/day

Let, quantity of total work = a

According to problem,

⇒ 5 × 3x + 10 × 2x = 0.7a

⇒ 0.7a = 35x

⇒ a = 50x

Let, they together do the work in = y days

⇒ y × (3x + 2x) = 50x

⇒ y = 50x/5x

⇒ y = 10

∴ They together will complete the work in = 10 days

Related Questions

Each question below is followed by two statements I and II. You have to determine whether the data given in the statement is sufficient for answering the question. You should use the data and your knowledge of Mathematics to choose the best possible answer. P, Q and R together can complete a work in 12 days. All of them worked together for 6 days and then P left. How much time will Q and R together will take to complete the remaining work? I. If P completes a work in X number of days, then Q and R together complete the work in X number of days. II. After leaving the work, P completed another work in 10 days.