Question

Jay and Anup can do a job, each working alone in 30 and 15 days respectively. Jay started the work and after a few days, Anup joined him. They completed the work in 18 days from the start. After how many days, did Anup join A?___

Answer 1

Since Jay does $(\frac{1}{30}{)}^{th}$ of the work in one day, total work done by Jay in 18 days

$=\frac{18}{30}=\frac{3}{5}$

Remaining $(\frac{2}{5}{)}^{th}$ work was done by Anup

Since Anup does $(\frac{1}{15}{)}^{th}$ of the work = 2/5/(1/15) $\frac{\left(\frac{2}{5}\right)}{\left(\frac{1}{15}\right)}$ = 6 days.

So, Anup joined Jay after (18−6) = 12 days.