Question 972801
One person can do a certain job in one-half hour, and another person can do the same job in one hour and ten minutes. How many minutes will they take to do the job together?
one-half hour = .5 hours
one hour and ten minutes = 1+10/60 = 1+1/6 = 7/6 hours
.
Let t = time (hours) it takes for both
then
t(1/.5 + 1/(7/6)) = 1
t(1/.5 + 6/7) = 1
t(1/.5 + 6/7) = 1
multiply both sides by 3.5
t(7 + 3) = 3.5
t(10) = 3.5
t = .35 hour
or
t = .35 *60 = 21 minutes