What are Permutations?

Let X represent the difference between the number of heads and the number of tails obtained when a coin is tossed n times.
What are the possible values of X?

Let X be a normal random variable with mean 12 and variance 4. Find the value of c such that P{X>c}=.10.

Based on the Normal model N(100, 16) describing IQ scores, what percent of peoples

There four foreign nationals in a group of fifteen people. Four people are chosen at random.

Although it’s hard to be definitive in classifying people as right- or left-handed, some studies suggest that about 14% of people are left-handed. Since ${\displaystyle 0.14\times 0.14=0.0196}$ the Multiplication Rule might suggest that there’s about a 2% chance that a brother and a sister are both lefties. What’s wrong with that reasoning?

An electronics store sells warranties on a $200 item for $15. The probability that a customer exercises the warranty is 3%. If it costs $3 to administer each warranty, what is the expected profit per warranty sold?

Each year, a company either makes a profit or takes a loss. If the company made a profit the year before, they will make a profit with probability 0.7. If they took a loss the year before, they will make a profit with probability 0.3. What is the long-run probability the company will make a profit?