In a controlled laboratory environment, independent random samples of 10 adults and 10 children were tested by a psychologist to determine the room temperature that each person finds most comfortable.  The study provided the following results:                                               Adults         Children Sample size                            10                 10 Sample mean (in degrees)   77.5              74.5 Sample variance                       4.5                2.5 Which one of the following is the correct 99% confidence interval for the true difference in population mean temperatures that adults and children find most comfortable?

The variables, quantitative or qualitative, that are related to a response variable are called:

Assuming equal numbers of observations in each of the two samples, find the sample sizes needed to estimate the difference in population means correct to within 2.5 with probability 0.90.  From prior experience, we know that the standard deviation of population 1 is 18 and the standard deviation of population 2 is 16.

Suppose x has a binomial probability distribution with n = 200 and p = 0.60.  Use the normal approximation to the binomial to find P (X > 130).

The weights (in pounds) of 17 pigs are used to construct the following stem-and-leaf display (the first two digits were used as the stem and the last digit was used as the leaf): Stem                   Leaf                                       16          0     5 17          — 18          — 19          — 20          — 21          — 22          2     4     6 23          0     9 24          0     1     2     3     4     5     9 25          3 26          — 27          — 28          0     5   Based on this stem-and-leaf display, the median weight is __________ lb.

USA Today reported the results of a study that suggests frequently heading the ball in soccer lowers players’ IQs.  A psychologist tested 60 male soccer players ages 14 to 29 who played soccer up to five times per week.  Players who averaged 10 or more headers per game had an average IQ of 103, whereas players who headed the ball one or fewer times per game had an average IQ of 112.  The experimental units in this study are:

The owner of Get-A-Way Travel has recently surveyed a random sample of 385 customers of the agency.  He would like to determine if the mean age of the agency’s customers is over 31 years.  If so, he plans to alter the destination of their special cruises and tours.  If not, no changes will be made.  He therefore wants to test:    Ho:  μ = 31 years    Ha:  μ > 31 years If he concludes that the mean age is over 31 years when in fact it is not over 31 years, he makes a ________ error.

A farmer weighs his calves on the day they are weaned.  The weight of the lightest calf is 300 lb and the weight of the heaviest calf is 650 lb.  Based on this information, which measure of variation could be calculated?

The computer science department wants to estimate the average length of time it takes students to complete a computer project correct to within 5 hours with probability 0.96.  They do not have an estimate of the standard deviation of the times, but they remember that last year the shortest time needed to complete the project was 6 hours and the longest time was 36 hours.  Given this information, find an appropriate estimate of the standard deviation of the length of time required to complete the computer project and then find the sample size needed to estimate the average length of time it takes students to complete the computer project correct to within 5 hours with probability 0.96.

Assume that we have a herd of 50 horses and that we want to select a random sample of 5 of the horses for an experiment.  We use a random number table to obtain the following set of random numbers: 06     11     42     42     53 Is this a legitimate random sample to use for the experiment?