Question

Kind of confused with this whole probability concept, i just need help with these here

Answer 1

For this case we have 0-9 possible digits (10) and 4 spaces for the code

Part a

The number of ways are using the multiplication principle:

10x9x8x7= 5040

Part b

p= 1/5040

Part c

If digits can be repeated we have this:

10x10x10x10= 10000