Discussion of Question with ID = 091 under Time-and-Work

This is the discussion forum for this question. If you find any mistakes in the solution, or if you have a better solution, then this is the right place to discuss. A healthy discussion helps all of us, so you are requested to be polite and soft, even if you disagree with the views of others. The question and its current solution has also been given on this page.

Advertisement

Question

A can do a piece of work in 39 days. B is 30% more efficient than A. In how many days will they complete the work if they work together?

A

$16{22/23}$ days.

B

17 days.

C

$17{1/23}$ days.

D

$17{2/23}$ days.

Soln.
Ans: a

Let us first calculate the one day work of B. One day work of A is given as $1/39$. If B is 30% efficient, then one day work of B is $1/39$ × $130/100$ = $1/30$. Putting x = 39 and y = 30 in the shortcut method, we get ${xy}/{x + y}$ = ${390/23}$, which is same as: $16{22/23}$.


Comments and Discussion