Question

Tiana can clear a football field of debris in 3 hours. Jacob can clear the same field in 2 hours. If they decide to clear the field together, how long will it take them?
A.) 50mins
B.) 1hr 5mins
C.) 1hr 12mins
D.) 5hrs

Answer 1

Answer:

6/5 hr, or 1 hr 12 min

Step-by-step explanation:

We're looking for the time required for two people to clear a field.

We'll end up with an expression that looks like:

  1 job

------------ = time

  rate

or

  1 job

-------------  this has dimensions of time (hr).

 1 job/hr

specifically, we evaluate the following expression:

        1 job

--------------------------------

1 job       1 job

-------- + --------

 3 hr        2 hr

This simplifies to

      1                 1

-------------- = ----------- = 6/5 hr, or 1 hr 12 min

 1/3 + 1/2        5/6