189. The inside dimensions of a rectangular wooden box
are 2 inches by 4 inches by 6 inches. A cylindrical
canister is to be placed inside the box so that it stands
upright when the closed box rests on one of its six
faces. Of all such canisters that could be used, what is
the radius, in inches, of the one that has maximum
volume?  Pick one:
A) 2
B) 4
C) 5
D) 6
E) 8
Since the radius is squared, the biggest volume cylinder will have the biggest possible radius. To achieve that, let the smaller dimension of the rectangular box be the height. So, it will have 6x4 width x length. The biggest cylinder must fit both dimensions, so it must have at most a diameter of 4, so the radius will be 2.   2
<result>A</result>
189. The inside dimensions of a rectangular wooden box
are 2 inches by 4 inches by 6 inches. A cylindrical
canister is to be placed inside the box so that it stands
upright when the closed box rests on one of its six
faces. Of all such canisters that could be used, what is
the radius, in inches, of the one that has maximum
volume?