Probability practice problems page 2:
More probabilty concepts to know:
If you have a big enough pool of trials (by having multiple people do something, or by doing something a large amount of times), even very unlikely things can happen
Probability is best for figuring out what will happen over the long term. Probability may not help you if you are deciding what to do once, but it can really pay off if you are doing something a lot of times.
Probabilities for events that are not equally likely can sometimes be put into a form where things are equally likely. If you have events that are equally likely, you can use a grid to help you solve the problem
Problems to practice:
1. If I have the pair of spinners below, what is the probability, when I spin both, that the sum will be 3? What is the probability of getting a sum of 5? What sum are you most likely to get?
2. Mystico the astrologer for a well read newspaper predicted that if you are
an Aquarius, you will soon hear from a friend you have not spoken to in a very
long time. For the purposes of this question, assume that "a very long
time" means more than 10 years, and that "soon" means this week.
Assume also that a large number of people read the column every day.
A. Is it likely or unlikely that this will happen to every Aquarius
who is over age 15? (Explain)
B. Is it likely or unlikely that this will happen to at least one Aquarius who reads Mystico’s column? (Explain)
3. I have two friends who live in different states, and both of them are named Kathy (they have never met each other)
Which is more likely and why?
A. They both named their daughter Mary
B. They have some personality traits that are remarkably similar.
4. In response to a discussion of how likely it is that a tornado would hit River Falls, your friend says that it is very unlikely. How could you change or rephrase the condition of "a tornado touching down in River Falls" to make it fairly likely?