Bunuel
[img]https://gmatclub.com/forum/download/file.php?id=38810[img][/img][/img]
In the figure above, AB represents a ramp and the circle represents a wheel that has radius 1.5 feet. If the wheel is rolled up the top of the ramp, which of the following is closest to the number of revolutions it will make?
(A) 1 2/3
(B) 2
(C) 3 1/2
(D) 5
(E) 10
Attachment:
2017-11-23_2026_001.png
In distance, D, problems with wheels and number of revolutions:
D = (circumference, c) * (# of revolutions), so# of revolutions = \(\frac{D}{c}\)
D = ramp AB length = hypotenuse
The 3x-4x-5x right triangle has multiplier of 3:
(5*3)= 15 = ramp AB length = D*
Circumference of wheel A
2πr = 2π(1.5) = 3π
\(c = (3)(3.14)\approx{9.4}\)# revolutions =
\(\frac{D}{c}=\frac{15}{9.4}\approx{1.59}\), or \(1.6\)Answer A
Bunuel , the first image of the figure does not show up, though the one in the spoiler does. I tried two browsers.
*OR Pythagorean theorem, \(9^2 + 12^2 = h^2\)
\(81 + 144 = 225 = h^2\)
\(\sqrt{h^2}=\sqrt{225}\) , so \(h=15\)