# Thread: Rate of change problem?

1. ## Rate of change problem?

Sorry, im not sure if this is a calculus problem. I think it is because i need to find out how long it takes to fill a cup of water - it's for my comp. sci. class. If someone could point me in the right direction on how to solve this it would be greatly appreciated, as i dont know what i should do first. Thanks.

A glass has the shape of a truncated cone of height 5 inches. Its top diameter is 3.5 inches and its base diameter is 2 inches. If water is poured into the glass at 2 gallons per minute, write a Matlab script to calculate how long it takes to fill the glass to the brim. One gallon is 7.5 cubic feet.

2. You can solve this problem without using calculus. Find the volume of the truncated cone by first determining what the cone would look like if part of it hadn't been cut off, and then take the volume of that cone and subtract the volume of the cut off portion. Once you have that, calculate the rate at which water enters the glass in cubic inches per minute, and then divide volume by rate to get time.

3. worked perfectly, thanks dude.