Question

5) Gina can do a job in 5 hours, Rudy in 6 hours. How long will it take them if they work together? Round to the

earest minute.

Answer 1

2 hours 44 minutes

Explanation:

call Gina G, and call Rudy R.

let 1 represent 100% of the job completed.

Gina can do it in 5 hours. So 5G = 1

Rudy can do it in 6 hours. So 6R = 1

Multiply 5G = 1 by 6:

30G = 6.

Multiply 6R = 1 by 5:

30R = 5.

we now have 30G = 6 and 30R = 5.

add these together:

30G + 30R = 5 + 6

30 (G + R) = 11

we want the right side to be 1 (because 1 is 100% of the job completed).

divide both sides by 11:

(30/11) (G + R) = 1.

that means it takes Gina AND Rudy, working together, 30/11 hours

= 2.7272 hours

= 2 hours and 44 minutes (to nearest minute)