Problema Solution
two chemical plants are polluting a lake. if plant a produces a predetermined maximum of pollutant twice as fast as plant b, and together they produce the maximum pollutant in 28 hours, how long will it take plant b alone?
Answer provided by our tutors
let
a = the hours that the plant a take to cause the maximum pollution of the lake thus the rate of the pollution 1/a lake per hour
b = the hours that the plant b take to cause the maximum pollution of the lake thus the rate of the pollution 1/b lake per hour
plant a produces a predetermined maximum of pollutant twice as fast as plant b
a = b/2
1/a + 1/b = 1/28
plug a = b/2 into the last equation
1/(b/2) + 1/b = 1/28
by solving we find
b = 84 hours
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plant b will need 84 hours to cause the maximum pollution of the lake.