Hypothesis Testing — Unit test Answers

Opal is collecting data on water levels in different parts of town. She notices that her sample data has a low-value outlier. Which statement must be true?

A normal distribution of data has a mean of 90 and a standard deviation of 18. What is the approximate z-score for the value 64?

Which set of population data is the least dispersed from its mean?

A city’s annual rainfall totals are normally distributed, and the probability that the city gets more than 43.2 inches of rain in a year is given by . If the standard deviation of the city’s yearly rainfall totals is 1.8 inches, what is the city’s mean annual rainfall?

Derek Jeter challenges Albert Pujols to a batting battle. Each will earn 1 point for a hit other than a home run and 4 points for a home run in each round. Which player should you back given the statistics in the table below? Note that home runs are included as hits in the table.Data for Two BattersBatterAt BatsHitsHome RunsJeter4881569Pujols44812526

The histogram below shows the number of weeks Jimmy spent different amounts of money to fill the gas tank in his car. If the graph is redrawn so that the scale on the y-axis begins with zero, which aspect of the graph will change the most?

Vladimir rolls a six-sided number cube 36 times. If getting a 3 is a success, what is the probability of a success?

The graph below shows the amount of time Misha spent outside over a 30-day period. How might the graph be considered misleading?

Laila guesses on all 20 questions of a multiple-choice test. Each question has 4 answer choices. What is the probability of a success and a failure for this experiment?

A company makes a product and has no way to determine which ones are faulty until an unhappy customer returns it. Three percent of the products are faulty and will cost the company $200 each in customer service and repairs. If the company does not refund the customer when repairing the item, how much should the company charge to make a profit of $2.00 per item?

A company has an opportunity to bid on three contracts. Determine which would be the best investment given the information in the table below.Probability of Profit and Loss by ContractContractProfit, Probability of ProfitProbability to Break EvenLoss, Probability of LossSoutheast$45,000, 50%30%$6,000, 20%Southwest$60,000, 35%40%$10,000, 25%California$112,000, 20%40%$40,000, 40%

The histogram below shows the estimated monthly salaries of company employees with different years of experience. How might the graph be misleading?

Car insurance companies want to keep track of the average cost per claim. The current data in use for Auto Insurance R Us is an average of $2,200 for each claim with a standard deviation of $500. With this average, the company can stay competitive with rates but not lose money. However, the statistician for the company believes that the cost of the average claim has increased. He pulled 40 recent claims and found the average to be $2,350. Which most restrictive level of significance would suggest that the company should raise rates? Upper-Tail Valuesa5%2.5%1%Critical z-values1.651.962.58

A textbook company states that the average time a student needs to take a quiz from its book is 30 minutes with a standard deviation of 3 minutes. A teacher using the book is not sure that this is correct for her classes and wants to check. She collects data on 10 random students and finds that the average time to take the quiz was only 25 minutes. As a result, the teacher performs a two-tailed hypothesis test with a significance level of 5%. Which conclusion is valid based on the results of the test?

Miguel Cabrera has had 369 at bats, and he has 127 hits and 21 home runs. (Note: The home runs are included in the hits data.) If he is challenged to a batting battle, what is the expected score of each at bat if he earns 1 point for each hit that is not a home run and 5 points for each home run?