Word problems

Question

1. Tom can paint a fence in 8hours. Huck can paint the same fence in  5 hours. How long would it take to put two coats of paint on the fence if Tom and Huck work together? Leave your answer in improper fraction form. (Hint : Make sure you factor in 2 coats of paint) show working.

 

 

2. Kim and Josh can clean a house together in 4 hours. If it takes Kim 7 hours to clean the house by herself, how long would it take Josh to clean the house alone? Leave your answer in improper fraction form. Show all working .

 

 

3. Jack can mow the baseball grounds in 6 hours; Mike can mow the same grounds in 5 hours; and Chris can mow the grounds in 4 hours . How long will it take to mow the baseball grounds if jack, Mike, and Chris work together? Set up an equation. 

Answer 1

1. Tom's rate is 1 fence in 8 hrs

Huck's rate is 1 fence in 5 hrs.

Let time to paint two coats = t

then rate * time = work done

(1/8+1/5)*t = 2

t = 2/(1/8+1/5) = 2/(5/40+8/40) = 2/(13/40) = 2*(40/13) = 80/13 hours

 

#2 and #3 are very similar problems so once you understand how to do 1, you can easily do the others