help needed for P3 maths Qn

Academic support for Primary 3

help needed for P3 maths Qn

Postby ksoh3000 » Wed May 08, 2013 10:57 pm

HI

Can anyone help me to solve this qn ?

28 chess mathces were played at a chess tournament. If each player was allowed to play only once with each other player, how many players were there altogether ?


Tks

ksoh3000
BrownBelt
BrownBelt
 
Posts: 592
Joined: Thu Jul 21, 2011 10:43 pm
Total Likes: 0


Re: help needed for P3 maths Qn

Postby SignorWinter » Wed May 08, 2013 11:00 pm

8 players.

SignorWinter
OrangeBelt
OrangeBelt
 
Posts: 37
Joined: Wed May 08, 2013 8:04 pm
Total Likes: 0


Re: help needed for P3 maths Qn

Postby ksoh3000 » Wed May 08, 2013 11:10 pm

Hi

The answer is 8 players. How do you get it ?

ksoh3000
BrownBelt
BrownBelt
 
Posts: 592
Joined: Thu Jul 21, 2011 10:43 pm
Total Likes: 0


Re: help needed for P3 maths Qn

Postby SignorWinter » Wed May 08, 2013 11:19 pm

Using a hypothetical first number. If 5 players participated, then the first player plays matches against the other 4 players. The second player has already played against the first player, and so has to play matches against only the other 3 players. In this manner, the second-last player has to play against only one player, and the last player has already played against all the players.


Hence: 4 + 3 +2 +1 = 10

After that, it's a little guess and check.

Tbh, for such questions in the exam, I've always used purely guess and check. Not sure if they still accept it though. There's an algebra formula for it, but I don't know if it's taught.

SignorWinter
OrangeBelt
OrangeBelt
 
Posts: 37
Joined: Wed May 08, 2013 8:04 pm
Total Likes: 0



Return to Primary 3