Mikko manufactures drinking glasses in the shape of cylinders. He wants all of the glasses to have the same fixed volume. This implies that the height of a given glass will vary inversely with the square of its diameter. One of his glasses has a diameter of 3 inches and a height of 4 inches. If another glass has a height of 9 inches, what should its diameter be?

Question

anonymous · Answer

easy as pie

anonymous · Answer

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anonymous · Answer

diameter will be 2 in

anonymous · Answer

You didn't show your work Harkirat

anonymous · Answer

ok here it is
 volume of first glass will be π*(3/2)^2 * 4 = π * 9/4 * 4 = 9π
let radius of second glass be r
its volume = π* r^2 *9 =9πr^2

since both have to have the same volume

9π = 9πr^2  ==> 9π/9π = r^2  = >  1 = r^2

so r = 1  diameter = 2r = 2*1 = 2

darthsid · Answer

Give a man a fish, he doesn't go hungry for a day. Teach him to fish, he never goes hungry. Or something like that.

The height of the glass varies inversely with the square of the diameter.
This means:
$$height = (constant) \times \frac{1}{diameter^2}$$

This means, 
$$height \times diameter^2$$ = constant.

Just make sure the products are the same for both, and you will be able to find your answer.