How To Solve Work Word Problems
Notice that we sum rates of work, just as we did with in the previous problems.We should now use the information that says that "When pipe A and B are both on, they can fill this pool in 4 hours".For example, if he works twice as fast as B, then Let's solve the 3 problems I started with using what we learned here. How long does it take for Worker B to finish the job if he works alone? Let's call X to the number of hours worker A needs to finish the job, and Y to the number of hours worker B needs to finish the job. We also know that when working at the same time, they need 2 hours.So, using the formula I gave you before: Rearranging terms, we get: We conclude that B needs 6 hours to complete the job when working alone. Painters A and B can paint a wall in 10 hours when working at the same time. How long would it take to each of them to paint it if they worked alone?If he needs 30 minutes (0.50 hours), then he can complete 1/0.50 = 2 jobs in one hour. Finally, given that they can complete jobs per hour; then how many hours do they take to complete one job? Notice that if someone works twice as fast as someone else then he needs half the time to finish the job; if he works 4 times as fast, then he needs 1/4 the time to finish the job, and so on.Thereofore, if X is the number of hours worker A needs to finish a job, and Y is the number of hours worker B needs to finish a job, then the statement "Worker A works N times faster than worker B" is "translated" as . When working at the same time as Worker B, they can finish the job in 2 hours.Using the formula I gave above, this means that we have the equation: We also know that "Painter B works twice as fast as A".
Let's call X to the number of litres per hour pipe A delivers and Y to the number of litres per hour pipe B delivers.
Let's call X to the number of hours painter A needs to finish the job, and Y to the number of hours painter B needs to finish the job.
We know that "painters A and B can paint a wall in 10 hours when working at the same time".
Since the pool has 10,000 litres, the fact that they can fill it in 4 hours implies that when they are both turned on, they can deliver 10,000 litres every 4 hours; or 10,000/4 = 2,500 litres per hour.
So we get the equation: Since we already know that X = 1000, then we conclude that pipe B can deliver 1,500 litres per hour.
Since painter B is twice as fast, he would need 15 hours if worked alone. A 10,000 litre pool is filled by two pipes: A and B. When pipe A and B are both on, they can fill this pool in 4 hours. Notice that there is an important difference between the wording of this problem and the other two.