Question

Arun, Kartik and Mira can do a work in 90, 30 and 45 days respectively. If they work together, in how many days will they complete work?

Answer 1

Their rates of working are:

Arun: 1/90; Kartik: 1/30; Mira: 1/45 of the work per day.

Working together then can complete:

1/90+1/30+1/45=1/90+3/90+2/90=6/90=1/15 of the work in a day.

So it would take them 15 days to complete the work together.

Let's check the result. In 15 days Arun would be able to do ⅙ of the work, Kartik ½ the work, and Mira ⅓ the work. ⅙+½+⅓=1, so all the work would be completed in 15 days.