Saturday, November 14, 2009

Work Problem 4 Solution

This is the solution to the algebra work word problem # 4 which read: "Joe and Jim paint a house. Joe can paint it alone in 5 days, Jim in 8 days. They start to paint it together but after 2 days Jim stops. How long will Joe finish it alone?"

Joe takes 5 days
Jim 8
to paint a house

So Joe can do 1/5 of his job in one day and Jim can do 1/8th of his job in 1 day. If you just take Joe for example you can see where I'm heading on solving this problem. Joe can do 1/5th of his job in one day. So how long would he finish his job -- well besides knowing the answer already -- you would set it up as x/5 = 1. 1 being when the job is complete not just a "fraction" of his work being done. So the answer is 5 of course 5/5 = 1. You use this exact same method to solve the problem for both Joe and Jim.

**********Correction************ I realized I solved the problem before if they both continued working the job, but this problem states JIM stops working in 2 days. So Joe does x/5 part of his job in 2 days? 2/5 and Jim does x/8 part of his job in 2 days? 2/8, and Joe keeps working. So the equation would be

2/5 + 2/8 + x/5 = 1 multiply by 40 and get
16 + 10 + 8x = 40

26 + 8x = 40
8x = 40 - 26
8x = 14
x = 14/8 or 1 and 3/4ths so it would take 1 and 3/4ths days more for Joe to finish the job alone..


  1. please answer..:

    "A and B working together can complete a job in 30 days. After they had both worked 18 days, however, A left and B finished the work in 20 more days. Find the time in which each can do the work alone"..

    I would greatly appreciate it.. thank you!

  2. They start to paint it together but after 2 days Jim stops. How long will Joe finish it alone?"

  3. been busy - i will answer this when i can --

  4. Hey submitted the correction for this problem!

  5. can u show us ur solution on ur answer A=75, B=50

  6. aha. funny. funny, i wasted hours to solve this.

  7. What is A=75 and B=50 referring to ? lol he gave the answer in the problem above its right

  8. A + B do 1/30th of one complete job (1) per day
    After 18/30ths of the job was complete, A left
    B completes 1/b Of one complete job a day on his own, and it took him 20 days to finish

    1 – 18/30 = 20/b
    12/30 = 20/b
    12b/30 = 20
    12b = 600
    b = 50, or 1/50th of the entire job a day (not just the remaining work after A slacked off)

    30/a + 30/50 = 1
    30/a = 20/50, or 2/5
    30 = 2/5a
    150/5 = 2/5a
    75 = a

  9. saan nakuha ang 30/50?

  10. as i can see here this is the most short way of how to answer this kinds of questions, on other explanations its long and need to use fractions more but here its a short way and is very helpful for timed answering. this is great. keep it up.


Interested in improving you brain the fun way? Check out