The number of hours a battery lasts before failing varies from battery to batter

Question

The number of hours a battery lasts before failing varies from battery to battery. The distribution of failure times follows an exponential distribution which is strongly skewed to the right the central limit theorem says that: a. As we look at more and more butteries, their average failure time gets ever closer to the true population mean (mu) for all batteries of this type. b. The average failure time of a large number of batteries has a distribution of the same shape (strongly skewed) as the distribution for individual batteries. c. The average failure time of a large number of batteries has a distribution that is close to normal. d. The average failure time is not knowable because averages are less variable then individual observations. A study attempts to determine whether a football filled with helium travels farther when kicked than one filled with air. Each subject kicks twice: once with a football filled with helium and once with a football filled with air. The order of the type of ball kicked is randomized. This is an example of: a. A matched pairs experiment b. A randomized controlled experiment c. A stratified experiment d. The placebo effect Many sample surveys use well-designed random samples but half or more of the original sample can't be contacted or refuse to take part. Any errors due to this nonresponse: a. Have no effect on the accuracy of confidence intervals. b. Are included in the announced margin of error c. Arc in addition to the random variation accounted for by the announced margin of error. A marketing class designs two videos advertising an expensive Mercedes sports car. They test the videos by asking fellow students to view both (in random order) and say which makes them more likely to buy the car. Mercedes should be reluctant to agree that the video favored in this study will sell more cars because: a. The study used a matched pairs design instead of a completely randomized design b. Results from students may not generalize to the older and richer customers who might buy a Mercedes c. The study was an observational study, not an experiment d. The sample was not selected at random, so the study cannot claim a causal relationship. For the following questions, carefully read the statements and indicate whether the statement is true or false. Each question is worth 2 points. As the sample size increases, the standard error of the sampling distribution of the sample proportion increases. Always do data analysis before inference to detect outliers or other problems that would make inference untrustworthy.

Explanation / Answer

The above answers are

12.   a

13.   a

14.   c

15.   b

16.   false

17.   true

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