M7MBA wrote:Each student at a certain business school is assigned a 4-digit student identification number. The first digit of the identification number cannot be zero, and the last digit of the identification number must be prime. How many different student identification numbers can the school create?

A. 9,000
B. 3,600
C. 2,700
D. 2,592
E. 1,944

Number of options for the 1st digit = 9. (Any digit 1 through 9)
Number of options for the 2nd digit = 10. (Any digit 0 through 9)
Number of options for the 3rd digit = 10. (Any digit 0 through 9)
Number of options for the 4th digit = 4. (Must be 2, 3, 5 or 7)
To combine the options above, we multiply:
9*10*10*4 = 3600.

The correct answer is B.

From the question, there are 4 digit number
*First digit cannot be 0 , which means it can be any of the digit between 1 to 9= ways of selecting first digit
*Second digit can be any of 0-9 which means 10 ways of selecting second digit
*Third digit can be any of 0-9 also which means 10 ways of selecting third digit and there is no information that indicates whether the numbers cannot be repeated
*Fourth digit can only be prime numbers which means fourth digit can only be 2,3,5,7=4ways of selecting fourth digit.

Total student identification number that can be created = $$9ways\cdot10ways\cdot10ways\cdot4ways=9\cdot10\cdot10\cdot4=3600\ student\ I.D\ \ number$$

Option B is very correct