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mathematical problem
(1), A won the first place and C won the second place. The result of the competition is that A wins B, A wins C and B wins C,:1/3 *1/4 *1/3 =1/36.

(2)0 indicates that A failed in both games:

P(0)= 2/3 * 3/4 = 1/2

3 points means that A wins and loses, which can be divided into two situations: winning B and losing C and winning C and losing B:

p(6)=( 1/3 * 3/4)+(2/3+ 1/4)= 5/ 12

A scored 6 points, which means A won both games.

p(9)= 1/3 * 1/4 = 1/ 12

The distribution list is:

0 3 6

p 1/2 5/ 12 1/ 12

Mathematical expectations are:

e = 0 * 1/2+3 * 5/ 12+6 * 1/ 12 = 7/4

Respondents: a 37 15095 16a- novice level 312-118: 26.

( 1)

Team a won the first place and team c won the second place, that is, team a won 2 games and team c won 1 game.

The probability of A winning two games is1/3 *1/4 =112.

The winning probability of 1 is 1- 1/3 = 2/* 3.

The result of multiplying the two is118.

(2)

Team A may win 6 points in 2 games or win 3 points in 1 game or lose 0 points in 2 games.

The probability of A winning two games is1/3 *1/4 =112.

The probability that A wins 1 field is1/3 * 3/4+2/3 *1/4 = 5/12.

The probability of a 0 win is 2/3 * 3/4 = 1/2.

Expected value =112 * 6+5/12 * 3+1/2 * 0 = 7/4.