Question 584606
One person can complete a task in 3 minutes.
 A second person can complete the same task in 5 minutes.
 How long would it take to complete the task if the two people work together?
:
Let t = time required when working together
Let the completed job = 1
:
Each will do a fraction of the job, the two fractions must add up to 1
:
{{{t/3}}} + {{{t/5}}} = 1
Multiplying by 15 will clear the denominators, so we have
5t + 3t = 15
8t = 15
t = {{{15/8}}}
t = 1.875 min
or
1 + .875(60) = 1 min 52.5 sec