1. A club has 25 members.
i. Number of ways to choose four members of the club to serve on an executive
committee?
ii. Number of ways to choose a president, vice president, secretary, and treasurer of
the club, where no person can hold more than one office
Solution
i. It will be 25C4
or C(25,4)= 12650 ways
ii. P(25,4)
=25*24*23*22
=303600 ways
2. Ways five elements can be selected in order from a set with three elements when
repetition is allowed
Solution
Since each of the tasks can be completed in 3 different ways because we have 3 elements
to choose from, the total number of ways of selecting 5 elements will be
35=243
3. Probability that a fair die never comes up an even number when it is rolled six times
Solution
The probability that any given fair die roll appears up is ½ .
Since this rolls are independent, we have the probability of an odd showing up all 6 times
is ½6 =1/64