Unit Test — Unit test Answers

When finding the margin of error for the mean of a normally distributed population from a sample, what is , assuming a confidence level of 74%?

Veronique has a spinner with three sections of equal size, red (r), green (g), and blue (b).The spinner is spun twice. The sample space for the possible outcomes is S = {rr, rb, rg, gr, gg, gb, br, bg, bb}. If the number of times red is spun is the random variable, X, which graph represents the probability distribution?

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?

A simple random sample of size n is drawn from a normally distributed population, and the mean of the sample is , while the standard deviation is s. What is the 90% confidence interval for the population mean? Use the table below to help you answer the question.Confidence Level90%95%99%z*-score1.6451.962.58

The number of absences for one week for all students at a high school were compiled, and the probability distribution below was created. What is the probability in any given week that a randomly selected student will be absent no more than one day?Probability DistributionDays Absent: XProbability: P(X)00.7810.1420.0330.014050.04

A utility company hires pollsters to knock on random doors in different parts of town to survey residents about the cost of their electric bill. Would this study be biased? Why or why not?

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?

A gymnastics coach records the scores of a gymnast and develops the probability distribution below. What is the probability the gymnast scores a 9 or 9.5?Probability DistributionGymnastics Score: XProbability: P(X)50.025.50.0260.066.50.170.167.50.1480.188.50.189?9.50.02

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

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?

Voluntary sampling is one type of sampling method that is not probability based. This means that

Mrs. Gomes found that 40% of students at her high school take chemistry. She randomly surveys 12 students. What is the probability that at most 4 students have taken chemistry? Round the answer to the nearest thousandth.

The times taken to assemble a clock at a factory are approximately normally distributed with a given mean = 3 hr and standard deviation = 0.5 hr. What percentage of the times are between 2 hr and 4 hr?

The distribution of the values of a population is shown below, and a simple random sample is drawn from the population. Based on this information alone, can the sample be used to make inferences about the population?

A local newspaper compiles data on the number of days, X, people in a neighborhood receive the newspaper. The probability distribution for the data is shown in the table below. What is the probability that a randomly chosen person receives the newspaper at least one day per week?