Question

A locker combination has three nonzero digits, and digits cannot be repeated. The first two digits are 1 and 2. What is the probability that the third digit is 3?

A: 7/9

B: 1/3

C: 1/6

D: 1/7

Answer 1

D: 1/7
the possible outcomes are 1-9 and 1 and 2 have already been used so you have to have 3-9 and it’s 1 out of those 7 numbers

Answer 2

1/7

Explanation:

In the question, the possible digits are

1, 2, 3, 4, 5, 6, 7, 8, 9

Since, 0 is not allowed

The total number of possible digits are 9

The questions then says that 2 out of the 3 digits are 1 and 2, leaving the total number of possible digits to be 7

The numbers left are now;

S = {3, 4, 5, 6, 7, 8, 9}

The probability that the 3rd digit is 3 is 1 out of the seven possible values, since 3 is not repeated

Therefore,

Probability of 3 being the 3rd digit is 1/7.