A certain board game has a row of squares numbered 1 to 100

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metallicafan: Master | Next Rank: 500 Posts; Posts: 142; Joined: Sun Jun 12, 2011 7:55 amFollowed by: 3 members; Thanked: 5 times

by metallicafan » Thu Mar 01, 2012 6:48 am

A certain board game has a row of squares numbered 1 to 100. If a game piece is placed on a random square and then moved 7 consecutive spaces in a random direction, what is the probability the piece ends no more than 7 spaces from the square numbered 49?

(A) 7%
(B) 8%
(C) 14%
(D) 15%
(E) 28%

How should we understand the underlined phrase? It seems that we should analyze the probability of going right or left. But the OE doesn't mention that. Please explain.

OA D

Source: https://www.gmathacks.com

Source: Beat The GMAT — Problem Solving | Thu Mar 01, 2012 6:48 am

Jim@StratusPrep: MBA Admissions Consultant; Posts: 2278; Joined: Fri Nov 11, 2011 7:51 amFollowed by: 266 members; Location: New York; Thanked: 660 times; GMAT Score:770

by Jim@StratusPrep » Thu Mar 01, 2012 7:54 am

Honestly, that part does not even matter. The questions boils down to what is the probability of selecting a number between 42 and 56, inclusive out of the numbers 1 to 100. The rest is just fluff to get you confused.

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krusta80: Master | Next Rank: 500 Posts; Posts: 143; Joined: Mon Mar 14, 2011 3:13 amFollowed by: 5 members; Thanked: 34 times

by krusta80 » Thu Mar 01, 2012 8:16 am

metallicafan wrote:A certain board game has a row of squares numbered 1 to 100. If a game piece is placed on a random square and then moved 7 consecutive spaces in a random direction, what is the probability the piece ends no more than 7 spaces from the square numbered 49?

(A) 7%
(B) 8%
(C) 14%
(D) 15%
(E) 28%

How should we understand the underlined phrase? It seems that we should analyze the probability of going right or left. But the OE doesn't mention that. Please explain.

OA D

Source: https://www.gmathacks.com

Since there are only two possible directions, this just means it can go either left or right.

metallicafan: Master | Next Rank: 500 Posts; Posts: 142; Joined: Sun Jun 12, 2011 7:55 amFollowed by: 3 members; Thanked: 5 times

by metallicafan » Thu Mar 01, 2012 8:50 am

Thank you very much to both!

vishal.pathak: Master | Next Rank: 500 Posts; Posts: 176; Joined: Thu Sep 22, 2011 5:32 am; Thanked: 5 times

by vishal.pathak » Mon Mar 12, 2012 6:08 pm

metallicafan wrote:A certain board game has a row of squares numbered 1 to 100. If a game piece is placed on a random square and then moved 7 consecutive spaces in a random direction, what is the probability the piece ends no more than 7 spaces from the square numbered 49?

(A) 7%
(B) 8%
(C) 14%
(D) 15%
(E) 28%

How should we understand the underlined phrase? It seems that we should analyze the probability of going right or left. But the OE doesn't mention that. Please explain.

OA D

Source: https://www.gmathacks.com

Im confused, here is why

If the initial position is bet 35-49 then favorable condition is when the jump is towards 100
If the initial position is bet 49-63 then favorable condition is when the jump is towards 0

So reqd prob = (63-35+1)/2 = 14.5

What am I doing incorrectly?

Regards,
Vishal

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