Answer:
A. P("JQK" | "ACE")=0.2352
Explanation:
A. The definition of conditional probability for events in this case tell us that:
P("JQK" | "ACE")= P("JQK" ∩ "ACE")/P("ACE")
Where P("JQK") is the probability that the first card is a face card and P("ACE") is the probability that the second card is an ace.
Now we need to find P("JQK" ∩ "ACE") and P("ACE") to get what we are asked for.
P("ACE")=(48/52)(4/51)+(4/52)(3/51)
Because if the first card is not an ace, there will be 4 to choose in the second chance but if the first one is an ace, we will have 3 left to choose in the second chance. If we draw a tree diagram for this experiment, the cases above would be on different branches, so we add them.
P("ACE")=0.07692
And for P("JQK" ∩ "ACE"), we have the following:
P("JQK" ∩ "ACE")=(12/52)(4/51)
Because the first card must be a face card, it could not be an ace and after choosing one of the 12 face cards from the deck, there´s 4 aces left to take in the second chance.
P("JQK" ∩ "ACE")= 0.01809
Finally, we can use the definition of the beginning to find our answer:
P("JQK" | "ACE")= P("JQK" ∩ "ACE")/P("ACE")
P("JQK" | "ACE")= 0.07692 / 0.01809
P("JQK" | "ACE")= 0.2352