Which set of population data is the least dispersed from its mean?
C (6, 2, 2, 2)
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 ra
C (5%)
The proportions of multiple samples of registered voters who vote are normally distributed, with a mean proportion of 0.38 and a standard deviation of 0.0485. What is the probability that a sample chosen at random has a proportion of registered voters who
B (17%)
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?
D (0.14)
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 d
A (Her students, on average, do not take 30 minutes on the quiz, contrary to what the textbook company stated.)
A scientist calculated the mean and standard deviation of a data set to be mc026-1.jpg and mc026-2.jpg. She then found that she was missing one data value from the set. She knows that the missing data value was exactly 3 standard deviations away from the
B (14)
The times of all 15 year olds who run a certain race are approximately normally distributed with a given mean mc026-1.jpg = 18 sec and standard deviation mc026-2.jpg = 1.2 sec. What percentage of the runners have times less than 14.4 sec?
A (0.15%)
A researcher wants to survey people from different age groups to analyze voting patterns. Which type of survey will best accomplish this goal?
D (stratified sampling)
The times taken to assemble a clock at a factory are approximately normally distributed with a given mean mc022-1.jpg = 3 hr and standard deviation mc022-2.jpg = 0.5 hr. What percentage of the times are between 2 hr and 4 hr?
D (95%)
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 a
D (83%)
Weston completed a hypothesis test and found that he could not reject the null hypothesis. Which of the following is a valid reason for his conclusion?
D (The z-statistic lies outside the critical region.)
A supervisor finds the mean number of miles that the employees in a department live from work. He finds mc022-1.jpg and mc022-2.jpg. Which statement must be true?
C (z37 is between 2 and 3 standard deviations of the mean.)
The graph below shows the amount of time Misha spent outside over a 30-day period.
D (The y-interval shows exponential increase rather than linear increase.)
The graph below shows the amount of time Misha spent outside over a 30-day period.
A (The scale on the y-axis overemphasizes the difference in salaries between different experience levels.)
The grades of a science test are normally distributed. Thanh finds that his grade on the test has a z-score of -2.5. Which statement must be true?
A (Thanh's grade is 2.5 standard deviations below the mean of the test grades.)