1. Consider a multiple-choice test with ten questions. Each question has five answer choices, and only one answer is correct. If someone picks answers purely by guessing (at random), find the probability of obtaining 80% or better purely by guessing.

2. The mean weight, , of the US population is 140 lbs. with a standard deviation, , of 22 lbs. What will be the minimum weight of the top 80 percentile?

3. If you throw a die for two times, what is the probability that you will get a one on the first throw or a one on the second throw (or both)?

4. Fifty students took an Introduction to Chemistry exam. Assume that their scores formed a normal distribution with a mean of 80 and standard deviation of 4. The professor decided to adjust the scores by creating z scores. Only the first 2.5% of students got an A. Students were curious what actual scores would be As?

5.. Refer to the table which summarizes the results of testing for a certain disease.

PositiveTestResult NegativeTestResult

Subject has the disease 120 4

Subject does not have the disease 13 172 If one of the results is randomly selected, what is the probability that it is a false negative (test indicates the person does not have the disease when in fact they do)? What does this probability suggest about the accuracy of the test?