________ were originally used by Africans as a means of communication over long distances among family members and tribesmen.

Extra Credit:  Student A tried to pick up his sofa but discover that it is much heavier than he expected. What must occur in the muscle to increase tension so he can pick up this heavy piece of furniture?

Solve the problem.Complete the statement by filling in the blanks.The null hypothesis H0 is the statement of _________ and always has a ______ sign. The alternative hypothesis Ha is the __________ hypothesis. It is a statement about the value of a __________ that we intend to test.

According to Mars company, packages of milk chocolate M&M contain 20% orange candies. 500 candies are randomly selected form the daily production. We want to calculate the probability that the sample will contain more than 22% orange candies.What is the number of independent trials?

Obtain the required confidence interval for the difference between two population proportions. Assume that independent simple random samples have been selected from the two populations. A survey found that 31 of 60 randomly selected women and 38 of 73 randomly selected men follow a regular exercise program. Find a 95% confidence interval for the difference between the proportions of women and men who follow a regular exercise program.

Solve the problem.A researcher believes that the proportion of women who exercise with a friend is greater than the proportion of men. He takes a random sample from each population and records the response to the question, “Have you exercised with a friend at least once in the last seven days?” The null hypothesis is H0: pwomen = pmen. Choose the correct alternative hypothesis.

Find the indicated probability. Round to three decimal places.Assume that male and female births are equally likely and that the birth of any child does not affect the probability of the gender of any other children. Find the probability of exactly two girls in ten births.

Solve the problem.Which statement best describes the significance level of a hypothesis test?

Feature movie lengths (in hours) were measured for all movies shown in the past year in the U.S. The mean length of all feature length movies shown was 1.80 hours with a standard deviation of 0.15 hours. Suppose the length of a random sample of 20 movies was recorded from all movies released this year. The mean length of the feature length movies was found to be 1.72 hours with a standard deviation of 0.18 hours.In this example, the numerical values of 1.80 hours and 0.15 hours are .

Use the following information for the question. Male players at the high school, college and professional ranks use a regulation basketball that weighs 22.0 ounces with a standard deviation of 1.0 ounce. Assume that the weights of basketballs are approximately normally distributed.If a regulation basketball is randomly selected, what is the probability that it will weigh between 19.5 and 22.5 ounces? Round to the nearest thousandth.