A few days ago
Anonymous

Need help with a math word problem? Thx?

1) Worker A finshes the job in 8 days, and worker B finishes it in 12 days.

a) How many days will it take the two workers to finish the job?

b) If B worked alone for 3 days, how many days will it take A alone to finish the REMAINING work?

Top 4 Answers
A few days ago
blueskies

Favorite Answer

This is not an easy problem… But…

Problem 1. “part a)” is exactly the same problem as the one on the following link. Just in your case, Worker A is their Worker B, and your Worker B is their Worker A…. but it doesn’t really matter who is A or who is B… at least for the part a) part of the problem…

http://www.purplemath.com/modules/printpage.cgi?path=/modules/workprob.htm

Read the above link and see if their explanation helps…

Then come back here and read the solution that I’ve adjusted a bit…

If the first painter can do the entire job in 8 hours and the second painter can do it in 12 hours, then (this here is the trick!) the first guy can do 1/8 of the job per hour, and the second guy can do 1/12 per hour. How much then can they do per hour if they work together?

To find out how much they can do together per hour, I add together what they can do individually per hour: 1/8 + 1/12 = 5/24. They can do 5/24 of the job per hour. Now I’ll let “t” stand for how long they take to do the job together. Then they can do 1/t per hour, so 5/24 = 1/t. Flip the equation, and you get that t = 24/5 = 4.8 hours. That is:

hours to complete job:

first painter: 8

second painter: 12

together: t

completed per hour:

first painter: 1/8

second painter: 1/12

together: 1/t

adding their labor:

1/8 + 1/12 = 1/t

5/24 = 1/t

24/5 = t

They can complete the job together in just under 5 hours.

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A few days ago
Darlene
a) Set up ratios: (portion of job completed) / (time)

A: 1/8

B: 1/12

Working together, the time to complete the entire job is:

1/8 + 1/12 = 1/t

(3/24) + (2/24) = 5/24

5/24 = 1/t

t = (24/5) = 4 4/5 days.

b) Let ‘x’ denote the portion of the job B completes in 3 days.

x/3 = 1/12

x = 3/12 = 1/4

A completes (3/4) of the job. Let ‘x’ denote the number of days required to complete (3/4) of the job:

(3/4) / x = 1/8

x = (3/4) * (8) = 6 days.

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A few days ago
kickyouintheface
thats hard

say the job takes 24 units of work to complete. I picked this number at random cuz it’s easy to work with on this problem. Worker A does 3 units of work per day to finish the job in 8 days, and Worker B would do 2 units of work per day, because it takes him 12 days to finish. now:

a) if they’re both working together each day, that’s five units of work that’s getting completed each day (A’s 3 plus B’s 2), so it takes almost six days: 5.8 days (24 total units of work for the job divided by five units per day).

b) if B works alone for 3 days, 6 units of work would get done (B does 2 units per day, according to this model), leaving 18 units to be done. A will finish the remaining work in 6 days as A can do 3 ‘units’ per day. answer: 6 more days.

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A few days ago
Anonymous
a) it will take 20 days for the two workers to finish the job

b) it will take b 3 days to finish the work

idk im really rong thats a hard quetsion

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