SOLUTION: A man and a boy perform a task in 2 days. They completed one-half of the task with the the first day with the man working 8 hours and the boy working 10 hours. On the next day they

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A man and a boy perform a task in 2 days. They completed one-half of the task with the the first day with the man working 8 hours and the boy working 10 hours. On the next day they      Log On


   



Question 634365: A man and a boy perform a task in 2 days. They completed one-half of the task with the the first day with the man working 8 hours and the boy working 10 hours. On the next day they finish the task with the man working 4 hours and the boy working 15 hours. Find how many days it would take for each working alone to do the task.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A man and a boy perform a task in 2 days.
They completed one-half of the task with the the first day with the man
working 8 hours and the boy working 10 hours.
On the next day they finish the task with the man working 4 hours and the
boy working 15 hours.
Find how many days it would take for each working alone to do the task.
:
Let m = time required by the man working alone
Let b = time when boy works alone
Let the completed job = 1
:
First day
8%2Fm + 10%2Fb = 1%2F2
Next day
4%2Fm + 15%2Fb = 1%2F2
Multiply the above equation by 2, subtract the first equation
8%2Fm + 30%2Fb = 1
8%2Fm + 10%2Fb = 1%2F2
----------------------subtraction eliminates m, find b
0 + 20%2Fb = 1%2F2
Cross multiply
b = 40 hrs, the boy alone
:
Find m
4%2Fm + 15%2F40 = 1%2F2
reduce the fraction
4%2Fm + 3%2F8 = 4%2F8
4%2Fm = 4%2F8+-+3%2F8
4%2Fm = 1%2F8
Cross mult
m = 32 hrs, the man alone
;
:
Confirm solution
4%2F32 + 15%2F40 =
1%2F8 + 3%2F8 = 1%2F2