In: Statistics and Probability
An ordinary deck of 52 cards is well-shuffled, and then the cards are turned
face up one by one until a face card (K,Q,J) appears. Find the expected
number of cards that are face up. Show and explain plz
Answer:-
Given That:-
An ordinary deck of 52 cards is well-shuffled, and then the cards are turned
face up one by one until a face card (K,Q,J) appears.
we are given that the cards of an ordinary deck of 52 cards are turned face up one by one until an ace appears .we need to find the expected number of the cards that are face up.
Let X be the number of the cards to be turned face up until an ace appears. Then
we need to find
The expected value of a random variable X with the set of the possible values A and the probability mass function P(X) is defined as
Now ,we need to find
Let A be the events that no ace appears among the first cards that are turned face up and B be the event that cards turned face up is an ace.
Thus, we have
On using the law of multiplication ,we get
Thus, we get
On using the summation calculation ,we get