Question

By checking time records, a plumber finds that worker A can do a certain job in 12 hours. Worker B can do the same job in 9 hours. How many hours would the job take if the two plumbers worked together?

Options:
a. 5
b. 7/3
c. 7
d. 6

Answer 1

Worker A can complete the job in 12 hours, worker B can complete it in 9 hours. The combined work rate of the two plumbers is 7/36 of the job per hour. Therefore, it would take approximately 5.14 hours for them to complete the job together.

Step-by-step explanation:

To determine how long it would take for the two plumbers to complete the job together, we need to calculate their combined work rate. Worker A can complete the job in 12 hours, so their work rate is 1 job per 12 hours. Worker B can complete the job in 9 hours, so their work rate is 1 job per 9 hours.

To find their combined work rate, we add their individual work rates: 1/12 + 1/9 = 3/36 + 4/36 = 7/36. This means that together, they can complete 7/36 of the job in one hour.

To find the time it would take for the two plumbers to complete the job, we divide the total job (1 job) by their combined work rate (7/36): 1 ÷ (7/36) = 36/7 = 5.14 hours (rounded to the nearest whole number).