Algebra Question!?

Question

Barry can do a certain job in 5 hrs. Whereas If mike helps him, it takes them 4 hrs to do the job working together. How long would it take mike to complete the job by him self?

Please explain the concept behind this problem? What is a good way to approach problems like this?

Answer 1

Let B stand for the working speed of Barry's, and M for the working speed of Mike's.
B = 1/5
(B+M)4 = 1
M = (1/4 - 1/5) = 1/20
1/M = 20 hrs

Answer 2

Work Problem Procedure

Let 1/B = Barry's rate in doing the job
1/M = Mike's rate in doing the job
1/T = rate when working together

1/B + 1/M = 1/T

1/5 + 1/M = 1/4

1/M = 1/4 - 1/5

1/M = 1/20

Therefore M = 20 hrs length of time it would take Mike to finish the job alone

Answer 3

I wonder if this is meant to be a pure algebra question?
Having two workers may change the procedure for doing the job. One might assume that Mike could do the job in five hours by himself just as Barry could. We cannot assume that Mike is inefficient working alone.
There is insufficient information to know what expertise is required for the job and the relative levels of expertise and efficiency of Barry verses Mike.
The best way to approach any problem is to stop and think.
What is the person asking the question looking for? If it is an algebra teacher asking, it may be a pure algebra question.

Answer 4

let M = no. of hours to complete the job alone

4/5 + 4 / M = 1
4 M + 20 = 5 M
M = 20