SOLUTION: A clerk is assigned a job that she can complete in 8 hours. After she has been working for 2 hours, another clerk, who is able to do this job in 10 hours, is assigned to help her.

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A clerk is assigned a job that she can complete in 8 hours. After she has been working for 2 hours, another clerk, who is able to do this job in 10 hours, is assigned to help her.       Log On


   

Question 73405This question is from textbook
: A clerk is assigned a job that she can complete in 8 hours. After she has been working for 2 hours, another clerk, who is able to do this job in 10 hours, is assigned to help her. In how many hours will the clerks working together complete the job. This question is from textbook

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A clerk is assigned a job that she can complete in 8 hours. After she has been working for 2 hours, another clerk, who is able to do this job in 10 hours, is assigned to help her. In how many hours will the clerks working together complete the job.
:
Let t = number of hrs required to complete the job when working together.
:
Let the completed job = 1
:
The 1st clerk completed 2/8 = 1/4 of the job when the 2nd clerk joined in.
:
1%2F4+%2B+t%2F8+%2B+t%2F10 = 1
:
Multiply equation by 40 to get rid of the denominators, resulting in:
10 + 5t + 4t = 40
:
9t = 40 - 10
9t = 30
t = 30/9
t = 10/3 hrs to complete the job, that would be 2 hrs 20 min
:
:
Check solution t=10/3 using 10 + 5t + 4t = 40
10 + 5(10/3) + 4(10/3) =
10 + 50/3 + 40/3 =
30/3 + 50/3 + 40/3 = 120/3 = 40
:
How about this? Did it make sense to you?