Exam 1: Exploring and Understanding Data

The five-number summary of credit hours for 24 students in a statistics class is: Min Q1 Median Q3 Max 13.0 15.0 16.5 18.0 22.0 Which statement is true?

Human body temperatures taken through the ear are typically 0.5° F higher than body temperatures taken orally. Making this adjustment and using the 1992 Journal of the American Medical Association article that reports average oral body temperature as 98.2° F, we will assume that a Normal model with an average of 98.7° F and a standard deviation of 0.7° F is appropriate for body temperatures taken through the ear. a. An ear temperature of 97° F may indicate hypothermia (low body temperature). What percent of people have ear temperatures that may indicate hypothermia? b. Find the interquartile range for ear temperatures. c. A new thermometer for the ear reports that it is more accurate than the ear thermometers currently on the market. If the average ear temperature reading remains the same and the company reports an IQR of 0.5° F, find the standard deviation for this new ear thermometer.

The Postmaster of a city's Post Office believes that a Normal model is useful in projecting the number of letters which will be mailed during the day. They use a mean of 20,000 letters and a standard deviation of 250 letters. Draw and clearly label this model.

At a large business, employees must report to work at 7:30 A.M. The arrival times of employees can be described by a Normal model with mean of 7:22 A.M. and a standard deviation of 4 minutes. (SHOW WORK) a. What percent of employees are late on a typical work day? b. A psychological study determined that the typical worker needs five minutes to adjust to their surroundings before beginning their duties. What percent of this business' employees arrive early enough to make this adjustment? c. Because late employees are a distraction and cost companies money, all employees need to be on time to work. If the mean arrival time of employees does not change, what standard deviation would the arrival times need to ensure virtually all employees are on time to work? d. Explain what achieving a smaller standard deviation means in the context of this problem.

Embryonic stem cells A Pew Research survey asked Americans their feelings on medical use of embryonic stem cells. Say they surveyed 340 people and got the results summarized in the table. a. What percent of the moderates said it is morally acceptable? b. What is the conditional relative frequency distribution of belief for for conservatives? c. If you wanted to show the association between political affiliation and feelings toward medical use of embryonic stem cells, what kind of graph would you make? (Just name it.) d. Is there evidence of an association between political affiliation and feelings toward medical use of embryonic stem cells? Explain briefly.