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pradeepkaushal9518: Legendary Member; Posts: 1309; Joined: Wed Mar 17, 2010 11:41 pm; Thanked: 33 times; Followed by:5 members

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by pradeepkaushal9518 » Fri Oct 01, 2010 4:39 am

How many times did the wheel of a car make a 360-degree rotation if the car moved 60 meters in a straight line without slipping?

The diameter of the car wheel (including the tire) is 0.75 meter.
The car wheel made 35 full 360-degree rotations per second.
A Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D EACH statement ALONE is sufficient.
E Statements (1) and (2) TOGETHER are NOT sufficient.

A SMALL TOWN GUY

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Source: Beat The GMAT — Data Sufficiency | Fri Oct 01, 2010 4:39 am

shovan85: Community Manager; Posts: 991; Joined: Thu Sep 23, 2010 6:19 am; Location: Bangalore, India; Thanked: 146 times; Followed by:24 members

by shovan85 » Fri Oct 01, 2010 5:14 am

IMO A

1. we get the perimeter and divide the whole distance and get the number of rotations.

2. Full time taken by the tyre for 60Mts is not known.

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diebeatsthegmat: Legendary Member; Posts: 1119; Joined: Fri May 07, 2010 8:50 am; Thanked: 29 times; Followed by:3 members

by diebeatsthegmat » Sun Oct 03, 2010 7:55 pm

pradeepkaushal9518 wrote:How many times did the wheel of a car make a 360-degree rotation if the car moved 60 meters in a straight line without slipping?

The diameter of the car wheel (including the tire) is 0.75 meter.
The car wheel made 35 full 360-degree rotations per second.
A Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D EACH statement ALONE is sufficient.
E Statements (1) and (2) TOGETHER are NOT sufficient.

is C the answer?

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Jim@Grockit: GMAT Instructor; Posts: 641; Joined: Wed Jul 22, 2009 3:07 pm; Location: Madison, WI; Thanked: 162 times; Followed by:45 members; GMAT Score:760

by Jim@Grockit » Sun Oct 03, 2010 8:58 pm

shovan85 wrote:IMO A

1. we get the perimeter and divide the whole distance and get the number of rotations.

2. Full time taken by the tyre for 60Mts is not known.

This is what I think as well. Given any of the usual bits of information about a circle, you can find the rest of them, since they are based on the radius/diameter.

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goyalsau: Legendary Member; Posts: 866; Joined: Mon Aug 02, 2010 6:46 pm; Location: Gwalior, India; Thanked: 31 times

by goyalsau » Sun Oct 03, 2010 10:44 pm

diebeatsthegmat wrote:
pradeepkaushal9518 wrote:How many times did the wheel of a car make a 360-degree rotation if the car moved 60 meters in a straight line without slipping?

The diameter of the car wheel (including the tire) is 0.75 meter.
The car wheel made 35 full 360-degree rotations per second.

is C the answer?
Answer should Be A,
Because we just need the no. of rotations, It does matter whether the speed is fast or slow, In all the cases number of rotations of the circle will be same.

take this example.

radius is 7 m.
Circumference of the circle will be 44m

Now if car moves at 220 m per hour for 1 hour. circle will complete 5 full rounds in one hour to cover the distance of 220m
Now if car moves at 110 m per hour of 1 hour. circle will complete 2.5 rounds in one hour and only over the distance of 110m

If it has to travel 220 meters it has to complete 5 full rounds..

by this it is clear that any speed no. of rounds will we same to cover a particular distance.

Even i got it wrong when i solved it first..