7.) Given a standard, interval-level IQ test ( \(\mu \) = 100 and \(\sigma \) = 15), and assuming that intelligence is normally distributed, answer the following questions.

1. If anyone with an IQ greater than 135 is considered a genius, what percentage of people in the world should be geniuses?
2. If Desdemona's IQ score is 67, what is her score as a percentile rank?
3. Buffy was told that her IQ score, as a percentile rank, was a 67. What is her IQ score?
4. Skip is exactly of average IQ and realizes that he needs a life partner who is smarter than he is. However, he realizes that someone who is too smart may—how shall I phrase this delicately?—find him a little "dull." Thus, he decides that his eligible pool of life partners consists of people who are from 10 to 25 IQ points smarter than he is. What percentage of people in the world, purely on the basis
5. You want to do a study that involves per; whose IQs are in the "normal" range, from 70 to 130. How many people must you screen with IQ tests in order to find a sample of 50 people with IQs in this range?

9. For each scenario, (a) state the research question, and (b) select the appropriate statistical test.

1. A home economist decides to find out if it is true that one bad apple spoils the bunch. He gets 50 bushels of apples, each with 100 unspoiled apples in it and randomly divides them into two groups. In each bushel in one of the groups, he inserts a '`bad" apple and in each bushel in the other group he inserts a "good" apple. He then stores the bushels in a climate-controlled chamber for a month, after which he counts the number of spoiled apples per bushel.
2. A health outcomes research was curious to see how health status changed over time. She obtained a representative sample of people from the state in which she lived and had each person indicate his or her health status as 1, "good," or 2, "not good." Five years later, she contacted the people and again had they rate their health status on this two-point scale. Five years after the second assessment she contacted the people for a third and final time and again had them rate their health status on the two-point scale.
3. Though most of the people to whom I have taught statistics have been psychology majors, my impression is that some of my best statistics students have been non-psychology majors. And, contrary to the idea that men are better at math than women, I've been struck by how well women do in my stats class. So, I've decided to investigate how gender and/or major affect performance in my statistics class. I obtain a random sample of students from the hundreds to whom I have taught statistics and for each person I note three facts: (a) his or her gender, (b) whether he or she was a- psychology major, and (c) his or her total -accumulated points in my class.
4. A college administrator is concerned that grade inflation has been occurring over the years. He picks a "GenEd" class, first-year English composition, and finds out the distribution of grades (A, B, C, D. or F) for a random sample of students in 1976 and for a random sample of students in 2006.
5. At one university the top 5% of the class is supposed to graduate with honors. A university official had reason to believe that the university, suffering from the Lake Wobegon effect, an effect named after a mythical Minnesota town where "all the children are above average," was awarding more honors diplomas than it should. At a recent graduation there were 535 graduates, of whom 35 graduated with honors.

Group Practice 1

Group Practice 2

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