GRE Sample Test 1 Quantitative Reasoning 2

Question : 7 of 20

Marks: +1, -0

A rectangular ribbon of width x is wrapped around the circumference of a right circular cylinder of radius n, encircling the cylinder without overlap as shown in the figure above. The area of the ribbon is equal to the area of the base of the cylinder.
Quantity A : Z
Quantity B : N

Quantity A is greater.
Quantity B is greater.
The two quantities are equal.
The relationship cannot be determined from the information given.

Validate

Solution:

Plug In for the radius, n, and solve for x. Let’s make n = 3: The area of the base of the cylinder is now 9π, and the circumference of the base is 6π. The ribbon itself is a rectangle, and we now know both its area, which is the same as the area of the base, and its length, which is the same as the circumference of the base. Now we can solve for x, which is the other side of the rectangle: 6πx = 9π, so x =

{9π}/{6π}

, or

3/2

. Our value for n is greater than our value for x, so Quantity B is greater

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