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Mathematics in Senior High School: On the Probability of Science Mathematics in 201KLOC-0/Tianjin College Entrance Examination
(1) If you touch three white balls, it must be two in box A and one in box B.

P=[C(2,3)/C(2,5)]*[C( 1, 1)C( 1,2)/C(2,3)]

(2) There are several ways to win the prize: 1, touch the two white balls in box A; 2. Touch a white ball in box A and a white ball in box B. Therefore, p = c (2 2,3)/c (2,5)+[c (1,3) c (1, 2)] * [c (1.

(3) Ten

1

2

P

e(X)= 0+ 1 * P(X = 1)+2 * P(X = 2)

Add: If you don't understand anything, you can continue to ask. The following are three probabilities of the problem (3).

Get the winning probability from (2) (I didn't count it, let's set it as P)

P(X=0)=( 1-p)( 1-p)

P(X = 1)= 1-P(X = 0)-P(X = 2)

P(X=2)=p*p