an experienced painter can paint a house in 6hrs while it takes an apprentice painter 9hrs to paint the same size house, how long would it take for 2 of them

Question

together to paint a similar house?

Answer 1

Hi Tanisha,

 

This one took me some time to figure out the best way to complete.

 

First think about the rate it takes each of them to work in what fraction of a house they can complete in an hour.

profession: 1/6 houses/hr 

apprentice: 1/9 houses/hr

 

Next, since they will be working together combine their painting speed:

(1/6)+(1/9) = 5/18

 

That means working together they can complete 5 houses in 18 hours.

 

So 1 house can be done in 18/5 or 3.6hrs.

 

Note: Since time doesn't uses decimals 0.6hrs is the equivalent of 36 minutes, so the answer can be written as 3 hours and 36 minutes.

 

I hope this is understandable, let me know if you need more help.