Sam takes 5 hours mopping the while school with no breaks. Cassie takes 4 hours doing the same job. If Sam started on hour early and if Cassie started 2 hours kate, how long did it really take to finish the job together? They end at the same time.
Please help me! I would like some details please!
Please help me! I would like some details please!
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Sam's rate = 1/5 per hour
Cassie's rate = 1/4 per hour
Combined rate working together = (1/5 + 1/4) = 9/20 per hour
Cassie starts 3 hours after Sam at which time Sam will have completed 3/5 of the job.
Working together to complete the last 2/5:
t = (2/5)/(9/20) = 8/9 hours ≈ 53 minutes
The job will be complete after Sam works alone for 3 hours and Sam and Cassie work together for approximately 53 minutes.
Cassie's rate = 1/4 per hour
Combined rate working together = (1/5 + 1/4) = 9/20 per hour
Cassie starts 3 hours after Sam at which time Sam will have completed 3/5 of the job.
Working together to complete the last 2/5:
t = (2/5)/(9/20) = 8/9 hours ≈ 53 minutes
The job will be complete after Sam works alone for 3 hours and Sam and Cassie work together for approximately 53 minutes.
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243434567 hours