Question

Hello, could someone please help me out with these questions? Thank you!!

It takes 8 hours for one crew to clean an office building. It takes a second crew 10 hours to clean the same building. If the first crew works 2 hours and leaves and the second crew takes over to complete the job, how long will it take the second crew to finish cleaning the building?


Two RSM students are standing 20ft apart and spot Mrs. Rifkin. If they immediately run opposite directions with speeds of 300ft/min and 200ft/min, how many minutes will pass until they are 3,000ft apart?

Answer 1

1. 7.5 hours

2. 5.96 minutes

Explanation:

1. In 2 hours, the first crew will have completed 2/8 = 1/4 of the work. The second crew will need 3/4×10 hours = 7.5 hours to complete the work.

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2. The two students are separating at the rate of (300 + 200) ft/min = 500 ft/min. They will add 2980 ft to their initial 20 ft separation in ...

2980 ft/(500 ft/min) = 5.96 min