- - , 1 - . - - - , - - .
.
. - - -. , = + , , (+) = ()+() - . - - - : P(A+B) = = + = P(A) + P(B), n m - - N .
. , : P() = 1 - (). : P(A+B+...+N) = P(A) + P(B) +... + P(N), - . -, : P(A) + P(B) +... + P(N) = 1
. :
P(A+B) = P(A) + P(B) - P(A×B).
, : ', A'' B', B''. '' B'' , , . :
= A''×B'' º '' º '' º ×, P(C) = P(A'') = P(B'') = P(A×B).
P(A) = P(A')+P(A''), P(A') = P(A)-P(A'') = P(A)-P(A×B).
P(B) = P(B')+P(B''), P(B') = P(B)-P(B'') = P(B)-P(A×B).
A', B' : P(A+B) = P(A'+B'+C) = P(A') + P(B') + P().
, m 1, 2,..., m:
P(A1+...+ Am) = P(Ai) - P(Ai×Aj) + P(Ai×Aj×Ak) -...+(-1)m+1P(A1×A2×... ×Am).
: - - - = - . P(A+B++)=P(A)+P(B)++()
: - n - - m1 , - m2 . P(A)=m1\n, P()=m2\n. . -, 1 , - 1 -, - . + - m1+m2 , :
1: - , , 1: P(A)+P(B)++()=1, ,,, , .
,,, , +++, - , - , - = 1: (+++)=1 \ ,,, , : (+++)=()+()++()=1
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2: - = 1 ()+(`)=1 \ .
1. 30 : 10 , 5 15 . . . , .
( ) () = 10 / 30 = 1 / 3. ( ) () = 5 / 30 = 1 / 6. ( ), . P (A + B) = P (A) + P (B) = l / 3 + l / 6 = l / 2.