(Solved): 2/2 Question 1 (14 marks) A mystery toy box contains one of the 12 kinds of toys in a set of n ...
第2/2頁 Question 1 (14 marks) A mystery toy box contains one of the 12 kinds of toys in a set of newly released toys, where 4 of them are rabbits. Any purchase made costs
$10. Assume that the kinds of toys in the box are independent and the probability of obtaining each kind of toy is the same. (a) Suppose Karen has 4 purchases on the mystery toy box. (i) What is the probability that exactly 3 toys are rabbits? (ii) What is the expected number of toys which are rabbits? (b) If Karen obtains at least two toys which are not rabbits after spending
$40, she will stop having purchases on the mystery toy box. Find the probability that Karen will stop making purchases on the mystery toy box after spending
$40. (c) Karen and her 5 friends each spend
$40on the mystery toy box. What is the probability that none of them obtain exactly 3 rabbits?
