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A total of 512 players participated in a single tennis knock [#permalink]
01 May 2012, 20:26

3

This post was BOOKMARKED

00:00

A

B

C

D

E

Difficulty:

35% (medium)

Question Stats:

67% (02:09) correct
33% (01:20) wrong based on 254 sessions

A total of 512 players participated in a single tennis knock out tournament. What is the total number of matches played in the tournament? (Knockout means if a player loses, he is out of the tournament). No match ends in a tie.

A. 511 B. 512 C. 256 D. 255 E. 1023

I chose D, solved this way - after first 256 matches, remaing players 256 (those 256 who lost are knocked out), after another 128 matches, remaining players are 128, after 64 more matches, no of remainig players are 64, after 32, 32, after 16, 16, after 8, 8, after 4, 4, after 2,2, and then 1 - total 256 + 128+64+32+16+8+1 = 255 matches

However, the correct answer given is A 511, can anyone please exlain what's wrong in my approach? Thanks!

Re: A total of 512 players participated in a single tennis knock [#permalink]
01 May 2012, 22:00

2

This post received KUDOS

Expert's post

gmihir wrote:

A total of 512 players participated in a single tennis knock out tournament. What is the total number of matches played in the tournament? (Knockout means if a player loses, he is out of the tournament). No match ends in a tie.

A. 511 B. 512 C. 256 D. 255 E. 1023

I chose D, solved this way - after first 256 matches, remaing players 256 (those 256 who lost are knocked out), after another 128 matches, remaining players are 128, after 64 more matches, no of remainig players are 64, after 32, 32, after 16, 16, after 8, 8, after 4, 4, after 2,2, and then 1 - total 256 + 128+64+32+16+8+1 = 255 matches

However, the correct answer given is A 511, can anyone please exlain what's wrong in my approach? Thanks!

You've done everything right except calculation: 256+128+64+32+16+8+4+2+1=511.

Re: A total of 512 players participated in a single tennis knock [#permalink]
26 Feb 2013, 18:12

1- the 512 players will play 256 games --> 256 plyers will go out from these games 2- the remaining is 256 players, they will play 128 games --> 128 players will go out 3- the remaining is 128 players, they will play 64 games --> 64 players will go out 4- the remaining is 64 players, they will play 32 games --> 32 players will go out 5- the remaining is 32 players, they will play 16 games --> 16 players will go out 6- the remaining is 16 players, they will play 8 games --> 8 players will go out 7- the remaining is 8 players, they will play 4 games --> 4 players will go out 8- the remaining is 4 players, they will play 2 games --> 2 players will go out. 9- the remaining is 2 players, they will play 1 games --> 1 players will go out

Re: A total of 512 players participated in a single tennis knock [#permalink]
24 Jun 2013, 07:23

If you divide 512 by 2 recursively to factor: 512,256,128,64,32,16,8,4,2,1. so the answer narrows to down to either A or B. Since the last dividend is 1, the sum will be odd so it should be 511

Re: A total of 512 players participated in a single tennis knock [#permalink]
26 Dec 2013, 12:05

Bunuel wrote:

gmihir wrote:

A total of 512 players participated in a single tennis knock out tournament. What is the total number of matches played in the tournament? (Knockout means if a player loses, he is out of the tournament). No match ends in a tie.

A. 511 B. 512 C. 256 D. 255 E. 1023

I chose D, solved this way - after first 256 matches, remaing players 256 (those 256 who lost are knocked out), after another 128 matches, remaining players are 128, after 64 more matches, no of remainig players are 64, after 32, 32, after 16, 16, after 8, 8, after 4, 4, after 2,2, and then 1 - total 256 + 128+64+32+16+8+1 = 255 matches

However, the correct answer given is A 511, can anyone please exlain what's wrong in my approach? Thanks!

You've done everything right except calculation: 256+128+64+32+16+8+4+2+1=511.

Re: A total of 512 players participated in a single tennis knock [#permalink]
03 Jan 2014, 16:34

gmihir wrote:

A total of 512 players participated in a single tennis knock out tournament. What is the total number of matches played in the tournament? (Knockout means if a player loses, he is out of the tournament). No match ends in a tie.

A. 511 B. 512 C. 256 D. 255 E. 1023

I chose D, solved this way - after first 256 matches, remaing players 256 (those 256 who lost are knocked out), after another 128 matches, remaining players are 128, after 64 more matches, no of remainig players are 64, after 32, 32, after 16, 16, after 8, 8, after 4, 4, after 2,2, and then 1 - total 256 + 128+64+32+16+8+1 = 255 matches

However, the correct answer given is A 511, can anyone please exlain what's wrong in my approach? Thanks!

Re: A total of 512 players participated in a single tennis knock [#permalink]
20 Apr 2015, 03:47

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A total of 512 players participated in a single tennis knock [#permalink]
25 Jun 2015, 01:14

One of the best logics I've seen for these knockout questions is as follows:

In this question, there are 512 participants. And it takes ONE match to eliminate ONE player. So at the end of the day you need to eliminate everyone except the winner. ie. you need to eliminate 511 participants and naturally you need 511 matches for the same

gmatclubot

A total of 512 players participated in a single tennis knock
[#permalink]
25 Jun 2015, 01:14

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