Ben is driving on the highway at x miles per hour. (One mile equals 5,

Hi shasadou,

This question can be solved by TESTing VALUES.

We're told the speed is X miles per hour and the circumference of the tires is Y feet. The question asks how many revolutions each wheel will turn in 1 hour.

Let's keep the values small so the math will be easy:

X = 2
Y = 4

Now the speed is 2 miles per hour, so that's 2(5280 feet) per hour. I'm not going to do that math just yet though….

Since the circumference of the tires is 4 feet, we can figure out the number of revolutions by dividing the distance by 4…

2(5280)/4 = 5280/2 = 2640

When you plug in the above values for X and Y, only one answer matches 2640…

Final Answer:

GMAT assassins aren't born, they're made,
Rich

Number of Revolutions/hr = Speed(in feet/hr)/Circumference(in feet)

= 5280x/y

Will questions like these appear in GMAT focus as they said Geometry has been removed?

 

­Which specific geomtry knowledge do you need to solve this question?

I guess the forumla comes from geometry. Circumference = Distance/ Rate

I may be wrong. That's why I am clarifying if i need to memorize these formulas. 

Calculating the number of revolutions using distance/circumference doesn't require specific geometry knowledge; it's a straightforward application of common sense. You simply divide the distance covered by the circumference of the wheel to find the number of revolutions.