credit quiz 11

Use this information to answer the next two questions. This is the distribution for the number of courses students take at a particular university. Number of Courses 1 2 3 4 5 6 7 Probability .02 .03 .09 .25 .40 .16 .05 What is the probability that students take only one or two courses?

0.05

What does the distribution of a random variable give us?

All possible values of the random variable and how often they occur.

Why can we say that the probability model shown below is a correct probability model? Number of Courses 1 2 3 4 5 6 7 Probability .02 .03 .09 .25 .40 .16 .05

Because all of the probabilities are between zero and one. Because the sum of all of the probabilities is equal to one. Because there is a probability assigned to each event. Answer: All of these

This histogram displays a sample of female bear weights. Which density curve would be the best model for the weights of these female bears?

Curve A

Students at a particular university are able to evaluate professors on a five point scale (a score of 1 meaning poor teaching and a score of 5 meaning excellent teaching). What type of random variable is professor evaluation an example of?

Discrete

Referring to the eight possible arrangements of girls and boys you wrote down, find the distribution of X (the number of girls the couple has). That is, what values can X take, and what are the probabilities for each value?

Distribution E: Value of X 0 1 2 3 Probability 1/8 3/8 3/8 1/8

What is a correct description of the median of a distribution that is described by a density curve?

The value that divides the area of the density curve in half.

Let X be the number of girls the couple has. Based on the eight arrangements, what is the probability that X = 2?

0.250

Use this information to answer the next three questions. A couple plans to have three children. There are eight possible arrangements of girls and boys. For example, GGB means the first two children are girls and the third child is a boy. All eight arrangements are (approximately) equally likely. Write down all eight arrangements of the sexes of three children Based on the eight arrangements, what is the probability of any one of these arrangements?

0.125

What is the probability that students take at least five courses (i.e., five courses or more)?

0.61