#10. Researchers want to develop a new type of flashlight battery

that lasts longer on average than the current battery. The current battery lasts an average of 8.1

hours. The null and alternative hypotheses are:

H0: = 8.1 hours

Ha: > 8.1 hours

Where is the mean life expectancy of all the new flashlight batteries. Mark each of the following as a type I error, a type II error or a correct decision or none of the above.

(a) The mean battery life is 8.1 hours.

(b) Based on sample data the manufacturer concludes the mean battery life is greater than 8.1 hours.

(c) The mean battery life is greater than 8.1 hours, and based on sample data the manufacturer concludes the mean battery life is greater than 8.1 hours.

(d) The mean battery life is 8.1 hours, but based on sample data the manufacturer concludes the

mean battery life is greater than 8.1 hours.

(e) The mean battery life is 8.1 hours and based on sample data the manufacturer concludes the

mean battery life is 8.1 hours.

#15. Fast food is often considered unhealthy because much of it is high in both fat and calories. Are fat and calories related? Here are the fat and calories of several brands of burgers.

Fat (in grams) Calories

19 410

31 580

34 590

35 570

39 640

39 680

43 660

( Here would be a scatter plot of this data, but I couldn't figure out how to post it)

C) The y-intercept of the regression line is 210.95 calories. What does the value of the y-intercept

tell you about the relationship between fat (in grams) and calories for burgers? Be VERY

SPECIFIC and use clear, complete sentences.

e) Use the regression line to predict the calories in a burger with 34 grams of fat. Round your

answer to 2 places after the decimal point. ( I'm deff overthinking this question, but I want to double check. I said that it was 585.)

F) What is the observed number of calories in a burger with 34 grams of fat? ( Now im certainly overthinking, but im not going to lose easy points, so idc.)

G) The value of the linear correlation coefficient is r = 0.9607. Use clear, complete sentences to explain what the value of r tells you about the linear relationship between fat and calories in a hamburger. ( This, I don't have a sensible answer.)

#13. In which of the following situations is it reasonable to use the t- interval procedure to obtain a confidence interval for the population mean? Assume the population standard deviation is unknown. Chose all that apply.

(a) n=10 and the population is normally distributed

(b) n= 10 and the population is highly skewed to the right

(c) n=50 and the population is normally distributed

(d) n=500 and the population is highly skewed to the right

(e) The t-interval procedure is not reasonable in any of these situations.

#12. Suppose you form a 95% confidence interval for a population

mean. Which of the following statements is true? Choose all that apply.

(a) The confidence interval you formed will contain the population mean 95% of the time.

(b) 95% of all possible confidence intervals will contain the population mean.

(c) The confidence interval you formed may or may not contain the sample mean.

(d) 95% of the time your sample mean will equal the population mean.

(e) 95% of the population will be contained in the confidence interval.