Unit Test Answers

Which graph shows a negative correlation?

The resting heart rates for 80 women aged 46–55 in a simple random sample are normally distributed, with a mean of 71 beats per minute and a standard deviation of 6 beats per minute. Assuming a 90% confidence level (90% confidence level = z-score of 1.645), what is the margin of error for the population mean?Remember, the margin of error, ME, can be determined using the formula .

The dot plot shows the number of words students spelled correctly on a pre-test.

Ms. Johnson uses a statistics program to analyze all the data collected by her students during a lab experiment about acceleration due to gravity. The program reports =31.5 and .What is the variance of the data? Round to the nearest tenth.

Which best describes a random sample?

A store manager is looking at past jewelry sales to determine what sizes of rings to keep in stock. The list shows the ring sizes purchased by the last ten jewelry customers.9, 7, 6.5, 7.5, 7, 8, 5, 6, 7.5, 8

The dot plot represents the amount of rain recorded by rain gauges in different locations around a city.

The table shows the estimated number of lines of code written by computer programmers per hour when x people are working.

Georgianna wants to use the linear model associated with the data in the table to make a prediction.

When making a statistical inference about the mean of a normally distributed population based on a sample drawn from that population, which of the following statements is correct, all else being equal?

A random sample of people is chosen to participate in a survey. For the survey results to be considered valid, which must be true of the random sample?

The residents of three towns were polled to find the percentage of residents who take a vacation in the summer or in the winter. Which is the joint relative frequency of those in Town 2 who take a summer vacation? Round the answer to the nearest percent.

Which values are correct? Select three options.

Which phrases describe the relationship between heart rate and daily intake of caffeine? Select two options.

The graph shows the distribution of hand lengths, in centimeters, of the members of an orchestra.

Ms. Sutton recorded the word counts and scores of the top ten essays in a timed writing contest. The table shows her data.How does the word count of an essay relate to its score in the contest?

Violet creates two spinners for a game. Each spinner is spun once, and the sum is recorded. The table represents the sums of the spinners and the frequency of each sum.

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Adriana, Henry, Malik, and Richard each design surveys to determine the most popular way seventh graders purchase music. Adriana samples the five friends sitting at her lunch table. Henry samples every boy in his homeroom class. Malik samples every student using an MP3 player while waiting for the bus. Richard samples the first student alphabetically on the class roster from each of 12 classes. Which sample is likely to produce the most valid results?

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 99% 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 graph shows the best-fit regression model for a set of data comparing the number of hours spent hiking and the number of miles traveled in one day.

Blanca runs 8 laps around the track each day to train for an endurance race. She times each lap to practice her pacing for the race. The table shows the lap times, in seconds, for three days of practice.Which histogram represents Blanca’s lap times for the three days of practice?

When finding the margin of error for the mean of a normally distributed population from a sample, what is the critical probability, assuming a confidence level of 58%?

A relative frequency table is made from data in a frequency table.

The two-way frequency table represents data from a survey asking mall visitors whether they like seafood, meat, or both. Which is the joint relative frequency for mall visitors who like seafood and meat?

Scientists studied a deer population for 10 years. They generated the function f(x) = 248(1.15)x to approximate the number of deer in the population x years after beginning the study. About how many deer are in the population 3 years after beginning the study?