Question

Paul can install a 300-square-foot hardwood floor in 18 hours. Matt can install the same floor in 22 hours. How long would it take Paul and Matt to install the floor working together?

4 hours
9.9 hours
13.2 hours
30 hours

Answer 1

B - 9.9 hrs

Explanation:

took the test.

Answer 2

9.9 hours

Explanation:

The formula to determine the time together is

1/a+1/b = 1/c where a and b are the times alone and c is the time together

1/18 + 1/22 = 1/c

The least common multiply of the denominators is 198c

198c(1/18 + 1/22 = 1/c)

11c+ 9c = 198

20c = 198

Divide by 20

20c/20 =198/20

c =9.9