The missing rate
Algebra
Level
pending
If one machine pumps a pool in four hours and a second machine pumps the same pool in three hours, how fast would a third machine have to be for all three machines to finish pumping the pool in one hour? Answer in pools per hour round to the nearest hundredths.
The answer is 0.42.
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1 solution
r a t e w o r k d o n e = t i m e The sum of all rates must equal 1 hour 4 1 + 3 1 + x = 1 1 2 7 + x = 1 x = 1 − 1 2 7 = 1 2 5 therefore the missing rate is 1 2 5 h o u r p o o l s rounded to the nearest 0.01=0.42