Bob and James are finishing the roof of a house =. Working alone, Bob can shingle the roof in 10 hours. James can shingle the roof in 16 hours. How long will it take them working together to shingle the roof? Round your answer to the nearest hundredth if necessary. A) 13 hours B) 26.67 hours C) 6.15 hours D) 0.04 hours
Mathematics · High School · Tue Nov 03 2020
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Bob can shingle 1 roof for every 10 hours of work. (1/10)
James can shingle 1 roof for every 16 hours of work. (1/16)
To find out what they can do together, you must add their rates of work together.
This will be the number to find how fast they can shingle 1 roof in t amount of hours (1/t)
1/10 + 1/16 = 1/t
8/80 + 5/80 = 1/t
13/80 = 1/t (cross multiply)
13(t) = 1(80)
13t = 80
t = 6.15
It would take them 6.15 hours to complete the roof together.