A possible attack on your combination-lock is a brute-force attack in which every possible input combination is tried. Given the original design with a combination of three numbers between 0 and 15, how many possible input combinations exist? How about for the modified design with a combination of four numbers?

Two students are discussing electricity that has a frequency of 60 hz. student a says that this type of electricity is referred to as ac. student b says that in this type of electricity, the electrons flow in only one direction. which of the following statements is correct? a. only student a is correct b. only student b is correct c. both of the two students are correct d. neither of the two students is correct