The number of permutations of the 25 letters taken 2 at a time (with repetitions) is:

The number of permutations of the 9 digits taken 4 at a time (with repetitions) is:

Each permutation of letters can be taken with each permutation of digits, therefore the total number of possible passwords is:
The answers are (-3,-12), (-2,-10), (5,4)
Answer:
the diameter is 1
Step-by-step explanation:
Since C = pi*d, solving for d would give 1
Answer:
Step-by-step explanation:
Since D=MV, we can infer that M=D/V
That is your equation----------------^