A right cylinder is to be constructed under certain limited

[I_need_a_700plus]

The following IR problem can be found in the IR section of the CAT exam.

Would someone be able to explain the answer in a different way from given explanation in the CAT exam? Thanks!

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A right cylinder is to be constructed under certain limited parameters. The height of the cylinder cannot be more than twice the radius, nor can the reverse be true. The combined lengths of the height and the radius cannot exceed 16, and both values must be integers.

Identify the radius and the height of the cylinder that will maximize the volume of the cylinder, given the restrictions listed above. Make only two selections, one in each column.

Radius Height Value
5
6
8
10
11

[RonPurewal]

The following IR problem can be found in the IR section of the CAT exam.

Would someone be able to explain the answer in a different way from given explanation in the CAT exam? Thanks!

please tell us what that explanation is. (we don't necessarily have access to all these things when we're using the forum.)

[RonPurewal]

anyway, here's an approach. (it might be the same as what is already there -- but i don't know what's already there.)

you want these things to be as big as possible. so, let's see how big they can be.

* remember that the sum of r + h can't be more than 16.
so...
if one of them is 11, the only workable value for the other one is 5.
if one of them is 10, the other one could be 5 or 6. clearly you'd want 6, since you are trying to maximize things.
if one of them is 8, then the other one could be 5, 6, or 8. again, the only one worth considering is the biggest one, so 8.

so, basically, there are three pairs of numbers to consider. since each pair could be r & h in either order, you've got five cases. (would be six, but 8 & 8 is only one case.)
* r = 11, h = 5
* r = 5, h = 11
* r = 10, h = 6
* r = 6, h = 10
* r = h = 8

now, just plug these into the formula (for the volume of a cylinder) and see which one gives you the biggest volume.

[VirajG187]

A right cylinder is to be constructed under certain limited parameters. The height of the cylinder cannot be more than twice the radius, nor can the reverse be true. The combined lengths of the height and the radius cannot exceed 16, and both values must be integers.

This is the question stem RonPurewal can you please put it in equation form this statement.
The height of the cylinder cannot be more than twice the radius, nor can the reverse be true

Thank you.

[tim]

By its very nature "can't be more" will not fit into an equation. Even if you were to put this into an inequality, I suspect that alone would not be of much use. The purpose of IR is to look at this information holistically and to use the constraints and boundary conditions to your advantage. Take another look at this one and see if you can figure out a good approach.