test36 #11

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 269
Joined: Sun Apr 01, 2007 5:41 am

test36 #11

by dunkin77 » Sun Apr 29, 2007 1:53 pm
11. A point on the edge of a fan blade that is rotating in a plane is 10 centimeters from the center of the fan. What is the distance traveled, in centimeters, by this point in 15 seconds when the fan runs at the rate of 300 revolutions per minute ?
(A) 750π
(B) 1,500π
(C) 1,875π
(D) 3,000π
(E) 7,500π


The answer is B) - but for some reason my answer was A). Can you help?

User avatar
Community Manager
Posts: 789
Joined: Sun Jan 28, 2007 3:51 pm
Location: Silicon valley, California
Thanked: 30 times
Followed by:1 members

Re: test36 #11

by jayhawk2001 » Sun Apr 29, 2007 6:20 pm
dunkin77 wrote:11. A point on the edge of a fan blade that is rotating in a plane is 10 centimeters from the center of the fan. What is the distance traveled, in centimeters, by this point in 15 seconds when the fan runs at the rate of 300 revolutions per minute ?
(A) 750π
(B) 1,500π
(C) 1,875π
(D) 3,000π
(E) 7,500π


The answer is B) - but for some reason my answer was A). Can you help?
In 60 seconds the fan rotates 300 times, so in 15 sec it will rotate
75 times.

Total distance covered = (perimeter of circle with radius as 10) * 75

= 2*pi*10 * 75
= 1500 * pi

Hence B

Legendary Member
Posts: 559
Joined: Tue Mar 27, 2007 1:29 am
Thanked: 5 times
Followed by:2 members

by Cybermusings » Mon Apr 30, 2007 12:48 am
A point on the edge of a fan blade that is rotating in a plane is 10 centimeters from the center of the fan. What is the distance traveled, in centimeters, by this point in 15 seconds when the fan runs at the rate of 300 revolutions per minute ?
(A) 750π
(B) 1,500π
(C) 1,875π
(D) 3,000π
(E) 7,500π

300 revolutions / min = 300 * 15/60 = 75 revolutions in 15 seconds
Distance of the point from center = 10 cm (or radius = 10)
1 revolution = 2*pie*r = 20*pie
Thus 75 revolutions = 75*20*pie = 1500pie

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 7222
Joined: Sat Apr 25, 2015 10:56 am
Location: Los Angeles, CA
Thanked: 43 times
Followed by:29 members

by Scott@TargetTestPrep » Mon May 20, 2019 6:16 pm
dunkin77 wrote:11. A point on the edge of a fan blade that is rotating in a plane is 10 centimeters from the center of the fan. What is the distance traveled, in centimeters, by this point in 15 seconds when the fan runs at the rate of 300 revolutions per minute ?
(A) 750Ï€
(B) 1,500Ï€
(C) 1,875Ï€
(D) 3,000Ï€
(E) 7,500Ï€
The distance traveled by the point in one revolution is equal to the circumference of the circle, which is 2 x π x 10 = 20π.

We must convert 300 revolutions per minute to revolutions per second: 300/60 = 5 revolutions per second. So in 15 seconds, the number of revolutions is 5 x 15 = 75 revolutions.

Thus, the total distance traveled is 20Ï€ x 75 = 1500Ï€.

Answer: B

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage