The events involved in the experiment are five selected from eight mascots, and * * * has the result of C 8 5.
Select five events that meet the requirements to form a complete "Olympic mascot". * * There are C 2 1 C 3 1 results.
∴ The probability that the five selected animals just form a complete "Olympic mascot" P= C 12? C 13 C 58 = 6 56 = 3 28。
(2) If the score is expressed by the meaning of the question, the value of ξ is 100, 80, 60, 40.
According to the probability formula of classical probability and mutually exclusive events's probability formula.
P(ξ= 100)= C 12？ C 13 C 58 = 3 28；
P(ξ=80)= C 23 ( C 22？ C 13 + C 12？ C 23 )+ C 33？ (C 22+C 23)C 58 = 3 1 56； P(ξ=60)= C 13 ( C 22？ C 23 + C 12？ C 33 )+ C 23？ C 33 C 58 = 18 56 = 9 28；
P(ξ=40)= C 22？ C 33 C 58 = 1 56。
The ∴ξdistribution list is
∴ Eξ= 300 28 + 2480 56 + 540 28 + 40 56 =75。