Solve a and b please Q-4:Consider the design of aа)communication system.i. How many three-digit phone prefixes that are usedto represent a particular geographic area (such asan area code) can be created from the digits 0through 9?ii. As in part i., how many three-digit phone prefixesare possible that do not start with 0 or 1,contain 0 or 1 as the middle digit?i. How many three-digit phone prefixes are possiblebutiii.in which no digit appears more than once in eachprefix?Suppose that an operating roomb)needs to nandle three knee, four hip, and fiveshoulder surgeries.i. How many different sequences are possible?ii. How many different sequences have all hip, knee,and shoulder surgeries scheduled consecutively?i. How many different schedules begin and endwith a knee surgery?

here use combination and permutation

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