Answer:
6.913 cubic-meters/second.
Explanation:
Volume of pyramid is.

and

we essentially need to compute derivative at h = 3.
but firs we need to write s in terms of h only, to do that we use the fact that ration of side to height of a pyramid is always constant, which means.

solving for s and substituting in Volume function gives.

and taking derivative with respect to time gives.

but we have been given that piece of information so.

at h = 3 in above we have finally.
