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Practice test 1, #20.
Justin can paint a fence in 5 hrs, while Austin can paint the same fence in 2 hours, while Gustin can paint the same fence in 2.5 hours. Approximately, how long will it take them if all 3 work together?
A. 50 mins
B. 55 mins
C. 45 mins
D. 1 hr, 5 mins
E. 1 hr, 10 mins
My answer:
(1/5)+(1/2)+(1/2.5)= 11/10 or 1hr, 6 mins (answer choice D is closest)
Destroyer answer:
(1/5)+(1/2)+(1/2.5)= 10/11 or 55 mins
Why does the fraction get flipped????
Justin can paint a fence in 5 hrs, while Austin can paint the same fence in 2 hours, while Gustin can paint the same fence in 2.5 hours. Approximately, how long will it take them if all 3 work together?
A. 50 mins
B. 55 mins
C. 45 mins
D. 1 hr, 5 mins
E. 1 hr, 10 mins
My answer:
(1/5)+(1/2)+(1/2.5)= 11/10 or 1hr, 6 mins (answer choice D is closest)
Destroyer answer:
(1/5)+(1/2)+(1/2.5)= 10/11 or 55 mins
Why does the fraction get flipped????