Answer the following questions
7132 '7 ( Chapters 6,7,8 Test... 13. A study of elephants wishes to determine the average weight of a certain subspecies of elephants. The standard deviation of the population is 1100 pounds. How many elephants need to be weighed so that we can be 95% confident to be accurate within 100 pounds? 14. A food snack manufacturer samples 20 bags of pretzels off the assembly line and weighed their contents. If the sample mean is 12.3 and the sample standard deviation is 0.24, find the 90% confidence interval of the true mean. 15. A random sample of 90 voters found that 43% were going to vote for a certain candidate. Find the 99% confidence interval for the population proportion of voters who will vote for that candidate. 16. You wish to estimate, with 99% confidence, the population proportion of US adults who read fiction books. You estimate must be accurate within 4% of the population proportion. a) Find the minimum sample size needed. b) Find the minimum sample size needed if a prior study found that 17% of US adults read fiction books. m l'Q 8 Dashboard Calendar To Do Notifications Inbox Show all formulae and work. Draw the normal distribution when needed. 1. Given the normal distribution curve shown 2. Find the probability P(z 8.7) = .9364, then what is the standard deviation of X? 0= 10 0= n Dashboard Calendar To Do Notifications Inbox7132 '7 ( Chapters 6,7,8 Test... 9. A pollster claims that the mean amount spent on Christmas gifts by an American family is $930 with a standard deviation of $180. What is the probability that the mean amount spent on Christmas gifts for a sample of 500 families is between $910 and $970? 10. In one city, 85% of eligible voters are registered to vote. If 425 randomly selected eligible voters are surveyed, what is the probability that at least 82% of those selected are registered to vote? 11. A sample of 26 different payroll departments found that the employees worked an average of 309.7 days a year with a standard deviation of 24.8 days. What is the 99% confidence interval for the average days worked for all payroll departments? 12. Out of 180 randomly selected adults in the United States who were surveyed, 74 exercise on a regular basis. Construct a 98% condence interval for the proportion of all adults in the United States. co l'Q 8 Dashboard Calendar To Do Notifications Inbox 7132 '7 ( Chapters 6,7,8 Test... 6. Mrs. Smith's reading class can read at a mean of 170 words per minute with a standard deviation of 22 words per minute. The top 5% of the class is to receive a special award. What is the minimum number of words per minute a student would have to read in order to get the award? 7. A drug manufacturer claims that a drug cures a rare skin disease 75% of the time. You will test this claim by testing the drug on 100 patients. Find the probability that at least 70 patients are cured. 8. A survey of a_ll lobster fishermen found that they catch an average of 36 pounds of lobster per day with a standard deviation of 6 pounds. If a random sample of 40 lobster shermen is selected, what is the probability that their average catch is less than 32 pounds? 9. A pollster claims that the mean amount spent on Christmas gifts by an American family is $930 with a standard deviation of $180. What is the probability that the mean amount spent on Christmas gifts for a sample of 500 families is between $910 and $970? co l'Q 8 Dashboard Calendar To Do Notifications Inbox
