SOLUTION: Workman A's rate of doing work is twice that of Workman B's. One day, A & B work together for 8 hrs, then B due to injury stops and A finishes the rest of the job in 2 hrs. How lon

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Workman A's rate of doing work is twice that of Workman B's. One day, A & B work together for 8 hrs, then B due to injury stops and A finishes the rest of the job in 2 hrs. How lon      Log On


   



Question 984471: Workman A's rate of doing work is twice that of Workman B's. One day, A & B work together for 8 hrs, then B due to injury stops and A finishes the rest of the job in 2 hrs. How long would it take B to complete the job alone?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Workman A's rate of doing work is twice that of Workman B's.
One day, A & B work together for 8 hrs, then B due to injury stops and A finishes the rest of the job in 2 hrs.
How long would it take B to complete the job alone?
:
let a = time required by A to do the job
He works twice a fast as B, therefore
let 2a = time required by B to do the same job
let the completed job = 1
:
A works a total of 10 hrs, B works 8 hrs
The shared work equation
10%2Fa + 8%2F%282a%29 = 1
Multiply equation by 2a, cancel the denominators and you have:
2(10) + 8 = 2a
20 + 8 = 2a
28 = 2a
a = 14 for A to do the job alone
then
2(14) = 28 hrs for B to do the job alone
:
;
See if that works out using decimals
10%2F14 + 8%2F28 = 1
.7143 + .2857 = 1