There are two possibilities, the missing card is a club card or the missing card is not a club card. The probability that the missing card is a club card is ¼, and the probability that it is not a club card is ¾.
Case I: When the missing card is a club card:
The probability that the two cards drawn are club cards =
Case II: When the missing card is not a club card:
The probability that the two cards drawn are club cards =
By Baye’s Rule,
The required probability =
Hence, option C is the correct option.
A | B | C | D | Average |
---|---|---|---|---|
3 | 4 | 4 | ? | 4 |
3 | ? | 5 | ? | 4 |
? | 3 | 3 | ? | 4 |
? | ? | ? | ? | 4.25 |
4 | 4 | 4 | 4.25 |