What's the minimum number of crop dusters needed to complete the job in 5 hours?

Question

Each crop duster who works for Gary's can dust half an acre of crops in 25 minutes. The company must dust 8 0.75-acre lots and 12 1.5-acre lots to complete a certain job. What's the minimum number of crop dusters needed to complete the job in 5 hours?

Answer 1

Anna,

 

There are two different size lots

 

0.75 acre and 1.5 acre

 

If a crop duster can dust 0.5 acre in 25 minutes, then they can dust .75 acre in 37.5 minutes (25*1.5).  That same crop duster can dust a 1.5 acre lot in 75 minutes (25 * 3).

 

We have 5 hours or 300 minutes.

In 5 hours a crop duster can dust

4  1.5-acre lots or

8  0.75-acre lots

 

There are 12 1.5-acre lots, so 3 dusters will be needed.  There are 8 0.75-acre lots, so 1 crop duster will be needed here.

 

3+1=4

 

They will need 4 crop dusters to complete the job in 5 hours.