2. For many computer tablets, the owner can set a 4-digit pass code to lock the device.

a. How many digits could you choose from for the first number of the pass code?

b. How many digits could you choose from for the second number of the pass code? Assume that the numbers can be repeated.

c. How many different 4-digit pass codes are possible? Explain how you got your answer.

d. How long (in hours) would it take someone to try every possible code if it takes three seconds to enter each possible code?

A. 10

B. 10

C. 10,000

D. 8 hours

Step-by-step explanation:

Firstly, we should know that the numbers are labeled 0-9.

A. 10 digits

B. We already took one digit, but we still have 10 choices left again as numbers can be repeated.

C. For the first number, we have 10C1 choices since we are selecting 1 out of 10 numbers. This is the case for all the 3 renaming numbers. Hence the total number of possible passwords are

(10C1) ^4 = 10,000 possible password combinations

D. That is (10,000*3) / 60 in minutes = 500 minutes = 500/60 = 8.3333, approximately 8hrs