John is trying to drain a swimming pool. He has two pumps, but he can only use one at a time. He knows that the time a pump take
s to drain the pool varies inversely with the power in watts of the pump. His old pump is a 40 watt pump, and it can drain the pool in 5 hours. How long would the job take if he uses his new 100 watt pump?
What do you mean this sentence? the time a pump takes to drain the pool varies inversely with the power in watts of the pump, The meaning would be : if we have a power in watts greater the time to drag the pool will be less because the relation between power and time is inverse.
40 watts--------------5 hours) 100 watts------------ x
because the relation between power and time is inverse, we multiply directly. 40 watts(5 hours)=100 watts x x=(200 watts hours) / 100 watts=2 hours.
Answer: the time would be 2 hours. (the new pump is faster)
