N1998 P2 Q6

A Personal Identification Number (PIN) consists of 4 digits in order, each of which is one of the digits 0, 1, 2, …, 9. Suzie has difficulty remembering her PIN. She tries to remember her PIN and writes down what she thinks it is. The probability that the first digit is correct is 0.8 and the probability that the second digit is correct is 0.86. The probability that the first two digits are both correct is 0.72. Find the probability that

1. the second digit is correct given that the first digit is correct,
2. the first digit is incorrect and the second digit is correct,
3. the second digit is incorrect given that the first digit is incorrect.