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Assume that different groups of couples use a particular method of gender selection and each couple gives birth to one baby. This method is designed to increase the likelihood that each baby will be a girl, but assume that the method has no effect, so the probability of a girl is 0.5. Assume that the groups consist of 21 couples. Complete parts (a) through (c) below. a. Find the mean and the standard deviation for the numbers of girls in groups of 21 births. The value of the mean is p = . (Type an integer or a decimal. Do not round.) The value of the standard deviation is c: = (Round to one decimal place as needed.) b. Use the range rule of thumb to nd the values separating results that are signicantly low or signicantly high. Values of girls or fewer are signicantly low. (Round to one decimal place as needed.) Values of girls or greater are signicantly high. (Round to one decimal place as needed.) o. Is the result of 18 girls a result that is signicantly high? What does it suggest about the effectiveness of the method? The result si nicantl hi h, because 18 irls is V irls.Aresultof18 irls would su est that the method 9 y 9 9 El 9 99 f (Round to one decimal place as needed.) Based on a poll, among adults who regret getting tattoos, 13% say that they were too young when they got their tattoos. Assume that five adults who regret getting tattoos are randomly selected, and find the indicated probability. Complete parts (a) through (d) below. a. Find the probability that none of the selected adults say that they were too young to get tattoos. (Round to four decimal places as needed.) b. Find the probability that exactly one of the selected adults says that he or she was too young to get tattoos. (Round to four decimal places as needed.) c. Find the probability that the number of selected adults saying they were too young is 0 or 1. (Round to four decimal places as needed.) d. If we randomly select ve adults, is 'l a signicantly low number who say that they were too young to get tattoos? V because the probability that Y of the selected adults say that they were too young is V 0.05. If a procedure meets all of the conditions of a binomial distribution except the number of trials is not fixed, then the geometric distribution can be used. The probability of getting the rst success on the xth trial is given by P(x) = p(1 p)x_1, where p is the probability of success on any one trial. Subjects are randomly selected for a health survey. The probability that someone is a universal donor (with group O and type Rh negative blood) is 0.15. Find the probability that the rst subject to be a universal blood donor is the sixth person selected. The probability is . (Round to four decimal places as needed.) A survey showed that 81% of adults need correction (eyeglasses, contacts, surgery, etc.) for their eyesight. If 8 adults are randomly selected, nd the probability that at least 7 of them need correction for their eyesight. Is 7 a signicantly high number of adults requiring eyesight correction? The probability that at least 7 of the 8 adults require eyesight correction is (Round to three decimal places as needed.) Is 7 a signicantly high number of adults requiring eyesight correction? Note that a small probability is one that is less than 0.05. O A. No, because the probability of this occurring is small. O B. Yes, because the probability of this occurring is small. 0 C. No, because the probability of this occurring is not small. 0 D. Yes, because the probability of this occurring is not small