Question

Ramesh can water all the plants in a big garden in
40 minutes. His sister Sarla takes 1 hour. If their
gardener Haneef joins them, they can water all
the plants in 15 minutes. How much time will the
gardener Haneef take if he waters the plants alone?​

Answer 1

Answer:

30 minutes

Step-by-step explanation:

This is the ans 30 minutes when gardener do it alone

Answer 2

Step-by-step explanation:

These type of questions are simple once you understand the underlying concept.

It's given that,

Ramesh waters the garden in 40 minutes

Sarla waters the same garden in 60 minutes

Let's find out what work each of them can do in 1 minute

For Ramesh it will be 1/40

and for Sarla it will be 1/60

So in 15 minutes Ramesh and Sarla together can do

15*(1/40 + 1/60) part of the work

15*5/120

5/8

Hence the remaining part of the work i.e., 3/8 will be done by the gardener in 15 minutes

So work done by gardener in 1 minute

3/8 * 1/15

1/40

Hence the gardener alone will take 40 minutes to complete the work.

Hope this is clear