Exam 8: Regression, Associations, and Predictive Modeling

What is the standard deviation of the 10 total warranty plans? What assumption does this calculation require? Do you think this assumption is reasonable?

What is the probability that three consecutive customers all get 20% discounts?

The auto insurance industry crashed some test vehicles into a cement barrier at speeds of 5 to 25 Mph to investigate the amount of damage to the cars. They found a correlation of r = 0.60 between Speed (MPH) and damage ($). If the speed at which a car hit the barrier is 1.5 standard deviations Above the mean speed, we expect the damage to be _?__ the mean damage.

Find the standard deviation of the number of repairs each year.

Repair bills An automobile service shop reported the summary statistics shown for repair bills (in $) for their customers last month. Min 27 Q1 88 Median 132 Q3 308 Max 1442 Mean 284 SD 140 a. Were any of the bills outliers? Show how you made your decision. b. After checking out a problem with your car the service manager gives you an estimate of "only $90." Is he right to imply that your bill will be unusually low? Explain briefly.

What is the probability that he will cast his line without success 20 times before finally succeeding the 21st time?

Do you think the association would be stronger or weaker if we used data from one month of the season?

Growth A scientist is running an experiment that involves waiting for a culture to grow. The average time for one experiment to run is 93 minutes with a standard deviation of 10 minutes. a. If the scientist is going to run five experiments, with a 7 minute set-up time in between each experiment, what is the average of the total time this will take? b. What is the standard deviation of the total time? c. What assumption did you need make the calculations in the previous two problems?

A survey of an introductory statistics class in Autumn 2003 asked students whether or not they ate breakfast the morning of the survey. Results are as follows: a. What is the probability that a randomly selected student is female? b. What is the probability that a randomly selected student ate breakfast? c. What is the probability that a randomly selected student is a female who ate breakfast? d. What is the probability that a randomly selected student is female, given that the student ate breakfast? e. What is the probability that a randomly selected student ate breakfast, given that the student is female? f. Does it appear that whether or not a student ate breakfast is independent of the student's sex? Explain.

Explain what your P-value means in this context.

Write the company's null and alternative hypotheses.

If the restaurant is open for 8 hours each day, what are the mean and standard deviation for the total number of workers in a day, respectively? (assume that the each hour is independent)

All but one of the statements below contain a mistake. Which one could be true?

A company sponsoring a new Internet search engine wants to collect data on the ease of using it. Which is the best way to collect the data?

What do your answers to the previous question tell you about the company's likelihood of making a profit?

Among a dozen eggs, three are rotten. A cookie recipe calls for two eggs; they'll be selected Randomly from that dozen. Which plan could be used to simulate the number of rotten eggs that Might be chosen? I. Let 0, 1, and 2 represent the rotten eggs, and 3, 4, …, 11 the good eggs. Generate two random Numbers 0-11, ignoring repeats. II. Randomly generate a 0, 1, or 2 to represent the number of rotten eggs you get. III. Since 25% of the eggs are rotten, let 0 = rotten and 1, 2, 3 = good. Generate two random numbers 0-3 and see how may 0's you get.

What is the standard deviation of the number of repairs that may be required during the three-year lease period? On what assumption does your calculation rest? Do you think this assumption is reasonable? Explain.

What level of significance did the research department use?

If my dresser drawer has 10 blue socks and 12 black socks and I randomly pull out two socks, what Are the chances that they are both black?

Does Procellera Antimicrobial Wound Dressing help injuries heal faster? Researchers checked Records of 38 patients who had been treated for acute or chronic wounds between 2010 and 2012. They found that those who had been treated with Procellera Healed almost twice as fast. This is a