Answer to Question #303186 in Math for Rawan saud

Question

Q−4:

a) Consider the design of a communication system.

i. How many three-digit phone prefixes that are usedto represent a particular geographic area (such as an area code) can be created from the digits 0 through 9?

ii. As in part i., how many three-digit phone prefixes are possible that do not start with 0 or 1, but contain 0 or 1 as the middle digit?

iii. How many three-digit phone prefixes are possible in which no digit appears more than once in each prefix?

b) Suppose that an operating room needs to handle three knee, four hip, and five shoulder surgeries.

i. How many different sequences are possible?

ii. How many different sequences have all hip, knee, and shoulder surgeries scheduled consecutively?

iii. How many different schedules begin and end with a knee surgery?