Question

Working together, two pumps can drain a certain pool in 3 hours. If it takes the older pump 7 hours to drain the pool by itself, how long will it take the newer pump to drain the pool on its own?
Do not do any rounding.

Answer 1

I guess we assume they both drain at a constant rate.

Answer 2

4 I think?

Answer 3

assuming yes
:)

Answer 4

hi,
let's say that the volume of the pool is "x" liters
then the rate at the older pump drain the pool is
x/7 liters per hour
and let's assume that the time newer pump will take to drain the pool "h" hours
then the rate at the newer pump drain the pool is
x/h liters per hour

If they start working together then the rate at which they drain the pool is
x/7 + x/h = (hx + 7x)/7h = x(7+h)/7h

now we know the time take when 2 pumps work together...
so..
rate x time = volume of the pool
x(7+h)/7h * 3 = x
3 (7 + h) = 7h
21 = 4h
h = 21/4 hours
yep!! that's the answer!!

hope this will help ya!!!

Answer 5

We can let \(V\) be the volume of the pool. \[
3(d_1+d_2)=V = 7(d_1)
\]

Answer 6

So \[
3d_1+3d_2=7d_1
\]

Answer 7

thanks team

Answer 8

u r welcome!!