Stats Unit 10 Written Exam 2024.

Stats Unit 10 Written Exam 2024. The distribution of time needed to complete a certain programming task is approximately normal, with mean 47 minutes and standard deviation 6 minutes. Which of the following is closest to the probability that a randomly chosen task will take less than 34 minutes or more than 60 minutes to complete? - CORRECT ANSWER 0.0303 There were 5,317 previously owned homes sold in a western city in the year 2000. The distribution of the sales prices of these homes was strongly right-skewed, with a mean of $206,274 and a standard deviation of $37,881. If all possible simple random samples of size 100 are drawn from this population and the mean is computed for each of these samples, which of the following describes the sampling distribution of the sample mean? - CORRECT ANSWER Approximately normal with mean $206,274 and standard deviation $3,788 A sample of size n will be selected from a population with population proportion p. Which of the following must be true for the sampling distribution of the sample proportion to be approximately normal? - CORRECT ANSWER Both np and n(1 - p) are at least 10 The mean and standard deviation of the sample data collected on continuous variable x are -0.25 and 0.03, respectively. The following table shows the relative frequencies of the data in the given intervals. IntervalRelative Frequency−0.34≤x≤−0.31−0.34≤x≤−0.310.02−0.31≤x≤−0.28−0.31≤x≤−0.280.15−0.28≤x≤−0.25−0.28≤x≤−0.250.33−0.25≤x≤−0.22−0.25≤x≤−0.220.36−0.22≤x≤−0.19−0.22≤x≤−0.190.11−0.19≤x≤−0.16−0.19≤x≤−0.160.03 Based on the table, do the data support the use of a normal model to approximate population characteristics? - CORRECT ANSWER Yes, because the distribution of relative frequencies is very close to the empirical rule for normal models. Based on records kept at a gas station, the distribution of gallons of gas purchased by customers is skewed to the right with mean 10 gallons and standard deviation 4 gallons. A random sample of 64 customer receipts was selected, and the sample mean number of gallons was recorded. Suppose the process of selecting a random sample of 64 receipts and recording the sample mean number of gallons was repeated for a total of 100 samples. Which of the following is the best description of a dotplot created from the 100 sample means? - CORRECT ANSWER The dotplot is approximately normal with mean 10 gallons and standard deviation 0.5 gallon. A fitness center piloted two new programs to help people reduce stress levels and maintain a healthy lifestyle. After one month, 112 of the 125 people who volunteered for a program in mindfulness reported a reduction in stress levels, and 110 of the 135 people who volunteered for a yoga program reported a reduction in stress levels. The fitness center wants to investigate whether there is a significant difference between the proportions of all people in the two programs who would report reductions in stress levels. Have the conditions for inference been met? - CORRECT ANSWER No, because the samples were not selected or assigned using a random method.