Question

Statistics:
How many different three-digit identification tags can be made if the first digit must be 5?

Answer 1

how many numbers are there from 500 to 599 ?

Answer 2

If repition are not allowed 5,4,3 or 5x4x3 = 60
if repition are allowed 5x5x5 = 125
am I correct? :)

Answer 3

there are 10 digits 0...9
It does not say repetition is not allowed, so assume repetition

the first digit is 5, so you have 1 choice
the 2nd digit can be any of 10, so 10 choices
last digit can be any of 10, so 10 choices

number of id tags: 1*10*10= 100

or just figure the ids will be all the numbers from 500 to 599 (which is 100 different numbers)