Question

It takes William 45 minutes to weed the garden. It takes his younger sister May 75 minutes to do the same job. If they work together, how long will it take them?

A. 25 minutes
B. 28 minutes
C. 36 minutes
D. 60 minutes

Answer 1

B. 28 minutes

Explanation:

According to the given statement,

William weeds the whole garden in 45 minutes, then in one minute he will weed 1/45 of the garden

and

similarly, 1/75 of the garden in one minute.

When they both will work together, they will weed (1/45+1/75) of the garden in one minute

Solving the equation:

=
`(1)/(45)+ (1)/(75)\\= (75+45)/(3375)\\ =(120)/(3375)\\ = 0.036`

Garden weeded in one minute by both = 0.036

So, number of minutes to weed whole garden = 1/0.036

= 27.77 minutes

Rounding off will give us: 28 minutes

So,

Option B is the correct answer ..