Problema Solution
A 5 hp pump can empty a pool in 5 hours. A smaller 2 hp pump can empty the same pool in 8 hours. The pumps are used together to begin emptying the pool. After 2 hours the 2 hp pump breaks down. How long will it take the larger pump to empty the pool?
Answer provided by our tutors
We will use the general equation (# pools emptied)=(rate in pools/hr)*(time in hr). We can write:
1=x(5)
1=y(8)
1=(x+y)2+xt
where 'x' and 'y' stand for the rates of the 5hp and 2hp pumps, respectively and t is the time that it will take the 5hp pump to empty the pool after the 2hp pump breaks down.
Using Algebrator to solve for t, we get:
t=7/4 hrs or 1.75 hours