How to find the time it takes for the water to flow at a certain velocity?

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Can someone please explain to me how to do question 2e? Thanks!

1 Answer
Sep 30, 2017

I tried this:

Explanation:

The rate of flowing or velocity is the derivative of your function WW:
W(t)=27000000-1000(30-t)^3W(t)=270000001000(30t)3
We want the time when we have 8000l/(min), so we have:
8000=3000(30-t)^2
Rearranging:
2.7=(30-t)^2
30-t=sqrt(2.7 )
change signs:
t=30-1.64=28.35min