Answer:
So it can be:
Letter Number Number (and any permutation: Number Letter Number, or Letter Number Number). Three times one case.
For Letter Number Number, there are 4 letters and two numbers. Since numbers cannot be repeated, both of them must be used, because there must be two numbers. So, indeed:
4 * 2 * 1 = 8, but any permutation, so 8 * 3 = 24 is the sample size.
Second question: Must be,
5 Letter 6, so 4 cases: P= 4/24 = 1/6
Third question. May be:
5 D 6, 6 D 5, 5 6 D, or 6 5 D
P = 4/24 =1/6, again!
Step-by-step explanation: