Discussion of Question with ID = 097 under Time-and-Work

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Question

A, B and C can independently complete a work in 18, 16 and 6 days respectively. B and C start the work together, but A joins them after 2 days. In how many days will the work be completed?

A

\$3{37/41}\$ days.

B

\$4{37/41}\$ days.

C

\$5{37/41}\$ days.

D

\$6{37/41}\$ days.

Soln.
Ans: a

Use the shortcut formula. If A, B, C can independently complete the job in x, y and z days, and A joins after n days, the work is completed in \${xyz}/{xy + yz + zx}\$ × \$(1 + n/x)\$ days. Putting the various values x = 18, y = 16, z = 6, n = 2, and simplifying, we get \${160/41}\$, which is same as: \$3{37/41}\$.