SOLUTION: A,B can do a piece of work 6,8 hours respectively.If they work for a day alternatively.Suppose A beginning the work,in how many days work will be completed? i think answer is 6 ³/

Algebra ->  Rate-of-work-word-problems -> SOLUTION: A,B can do a piece of work 6,8 hours respectively.If they work for a day alternatively.Suppose A beginning the work,in how many days work will be completed? i think answer is 6 ³/      Log On


   



Question 979565: A,B can do a piece of work 6,8 hours respectively.If they work for a day alternatively.Suppose A beginning the work,in how many days work will be completed?
i think answer is 6 ³/2.
please explain this question.

Answer by josgarithmetic(39618) About Me  (Show Source):
You can put this solution on YOUR website!
Your description might be better understood as, "A and B working independently and not at the same time on the same job, take 6 and 8 hours respectively". They can still work "ALTERNATELY" on a task.

WORKER________RATE, job/hours
A_____________1/6
B_____________1/8

Now, the rest of the description gives A and B working in alternation. Each is working on the job separately, not simultaneously. We could try making calculation at a very low level.

(1/6)*1+(1/8)*1+(1/6)*1+(1/8)*1+....=1

Try maybe using a variable for the number of day that EACH may possibly work alone, although the true result could be non-whole.
Say like, A and B each works x days.
x%2A%281%2F6%29%2Bx%281%2F8%29=1
x%281%2F6%2B1%2F8%29=1
x%284%2F24%2B3%2F24%29=1
x%287%2F24%29=1
x=24%2F7, which is 3%263%2F7 days.

Try to now go back to the lowest day to day level.
First let A work for 3 days and B work for 3 days, knowing that A and B never work on the same day.

%281%2F6%29%2A3%2B%281%2F8%29%2A3=j
%284%2F24%2B3%2F24%29%2A3=j
%287%2F24%29%2A3=j
j=7%2F8
-
This way, three days for A and three days for B, done in alternation,
completes only 7%2F8 of the job, and the work began with worker A. B worked last, so A does ONE MORE day...
-
%281%2F6%29%2A4%2B%281%2F8%29%2A3=j
%284%2A4%29%2F24%2B%283%2A3%29%2F24=j
16%2F24%2B9%2F24=j
25%2F24=j
This then is slightly MORE THAN 1 JOB.

Let me just summarize as much as to say, A will work for 4 days, and then B will have worked 3 days, plus most of the last day but not all of it.