Statistics and Probability - Test Test Answers

The table shows the ages of houses to the nearest year in a neighborhood. Using the age of the houses as the random variable, cap x , which graph shows the probability distribution, cap p sub cap x times x , of a randomly chosen house?

How can the graph be adjusted to show the skew?

The human resources manager at a company records the length, in hours, of one shift at work, cap x He creates the probability distribution. What is the probability that a worker chosen at random works at least 8 hours?

The graph shows the experimental probability of a runner finishing in first place (1), in second place (2), in third place (3), or not placing (4). Which of the following describes the probability distribution?

How do the mean and median change from plot 1 to plot 2?

What is the mean of the normal distribution shown?

How could the graph be redrawn so that the difference in monthly electric cost does not appear as great?

Why is the plot misleading?

Each person takes turns rolling two dice. If the sum is odd, the person playing odds gets points equal to the sum of the roll. If the sum is even, the person playing evens gets points equal to the sum of the roll. Note that the points earned is independent of who is rolling the dice. If Jessica is challenged to a game of Sums, which statement is accurate in every aspect in guiding her to the correct choice of choosing to play odds or evens?

Rina spins the given spinner 30 times. A success occurs when the spinner lands on a number that is greater than 6 What is the probability of a success and a failure for this experiment?

Which statement is true about the data set?

A spinner is divided into five sections numbered 1 through 5. Juana records the number the spinner lands on for each of 50 spins. She computes and graphs the relative frequencies for each number. Which of the following describes the probability distribution?

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 percent ?

What is the mean of the normal distribution shown?

For a standard normal distribution, find the approximate value of cap p times open paren negative 0 point 7 8 is less than or equal to z comma z is less than or equal to 1 point 1 6 close paren Use the portion of the standard normal table to help answer the question. z Probability 0 point 0 0 0 point 5 0 0 0 0 point 1 6 0 point 5 6 3 6 0 point 2 2 0 point 5 8 7 1 0 point 7 8 0 point 7 8 2 3 1 point 0 0 0 point 8 4 1 3 1 point 1 6 0 point 8 7 7 0 1 point 7 8 0 point 9 6 2 5 2 point 0 0 0 point 9 7 7 2

The mean of a set of credit scores is mu is equal to 690 and sigma is equal to 14 Which statement must be true about z sub 694 ?

The lengths of a particular snake are approximately normally distributed with a given mean mu is equal to 15 in. and standard deviation sigma is equal to 0 point 8 in. What percentage of the snakes are longer than 16 point 6 in.?

For a standard normal distribution, which of the following expressions must always be equal to 1 ?

Destiny performs a hypothesis test on a population with mu is equal to 115 and sigma is equal to 30 Her sample size is 25 with a mean of 120 point 4 Which of the following correctly depicts the z -statistic for this data?

A professor surveys his students about their opinions on how well he taught the course. He puts this survey on the last page of his final exam. Which type of bias will most likely have the strongest effect on the survey results?

Glenda checks the computer monitors made at her company for defects. It has been shown that 0 point 5 percent of the monitors are defective. She decides to check several monitors and record if they are defective. Which of the following will make this process into a binomial experiment?

A simple random sample of size n is drawn from a normally distributed population, and the mean of the sample is line segment x , while the standard deviation is s What is the 99 percent confidence interval for the population mean? Use the table to help you answer the question. Confidence Level 90 percent 95 percent 99 percent z to the ast th power -score 1 point 6 4 5 1 point 9 6 2 point 5 8

The resting heart rates for 80 women aged 46 minus 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 percent confidence level open paren 90 percent confidence level is equal to z - score of 1 point 6 4 5 close paren , what is the margin of error for the population mean? Remember, the margin of error, ME , can be determined using the formula ME is equal to the fraction with numerator z times s and denominator square root of n

The difference between an observational study and an experiment is that

According to a poll, 56 percent of voters support funding a new community center. A surveyor randomly selects 75 voters and asks each voter if he or she is in favor of the center. If being in favor of the center is a success, what is the probability of a success for this binomial experiment?

As a project for math class, two students devised a game in which 3 black marbles and 2 red marbles are put into a bag. First the players must decide who is playing black marbles and who is playing red marbles. Then each player takes a turn at drawing a marble, noting the color, replacing the marble in the bag, and then drawing a second marble and noting the color before returning it to the bag. The point scheme for the game is detailed in the table. Point Values for Marble Game Black Marble Points Red Marble Points Both black: plus 2 points Both red: plus 4 points Different colors: negative 1 point Different colors: negative 1 points Both red: 0 points Both black: 0 points If Seth is challenged to a game by a classmate, which statement is correct in all aspects in helping him make the correct choice?

Emi computes the mean and variance for the population data set 87 , 46 , 90 , 78 , and 89 She finds the mean is 78 Emi's Work sigma squared is equal to the fraction with numerator open paren 87 minus 78 close paren squared plus open paren 46 minus 78 close paren squared plus open paren 90 minus 78 close paren squared plus open paren 78 minus 78 close paren squared plus open paren 89 minus 78 close paren squared and denominator 5 is equal to the fraction with numerator 9 squared minus 32 squared plus 12 squared plus 0 squared plus 11 squared and denominator 5 is equal to the fraction with numerator 81 minus 1 comma 024 plus 144 plus 0 plus 121 and denominator 5 =(−678)/(5) is equal to negative 135 point 6 What is the first error she made in computing the variance?

A manager of a grocery store wants to determine if consumers are spending more than the national average. The national average is 150 point 0 0 dollars with a standard deviation of 30 point 2 0 dollars The manager collects 40 random receipts and finds that the average is 160 dollars Complete a hypothesis test with a significance level of 2 point 5 percent to determine if the average customer spends more in his store than the national average. Which of the following is a valid conclusion for the manager based on this test?

You are challenged to a lucky draw game. If you draw a face card open paren cap k comma cap q comma cap j close paren from a standard deck of cards, you earn 10 points. If you draw any other card, you lose 2 points. What is the expected value of a draw?

A teacher asks students to list the math lessons they learned on nine random school days in the past month. She evaluates the students’ performance on this assignment to get a general picture of how well students are taking notes. This teacher’s method is an example of

To conduct a survey about the type of phone service most people in Greenville prefer, 10 different blocks in the neighborhood are chosen. On these 10 blocks, 10 houses are selected at random, and then each resident of each of those houses is interviewed. This type of sampling method is

A set of data has a mean of 0 point 5 and a standard deviation of 0 point 0 1 A data point of the set has a z -score of 2 point 5 What does a z -score of 2 point 5 mean?

In Juneau, Alaska, the 30 -year annual snowfall average is 86 point 7 inches with a standard deviation of 40 point 4 inches. The last four years saw an average annual snowfall of 115 point 7 inches, 62 point 9 inches, 168 point 5 inches, and 135 point 7 inches. Hia performs a hypothesis test on this data to determine if the next 30 -year norm will have a different average if the trend from the last four years continues. She uses a significance level of 5 percent Which of the following is a conclusion that she may make?

Sonia rolls a six-sided number cube 12 times and records if she rolls a 2. What is the number of trials for this binomial experiment?

A high school student volunteers to present a report to the administration about the types of lunches students prefer. He surveys members of his class and records their choices. What type of sampling did the student use?

A local weather enthusiast wants to see if the last five summers have been warmer than normal for Eloy, Arizona. From the National Oceanic and Atmospheric Administration (NOAA), he knows the 30 -year average for July was 90 degrees with a standard deviation of 2.1 degrees The last five summers recorded have an average of 93.5 degrees If he uses A is equal to 5 percent , which of the following would be valid based on the data he has gathered?

The mean test scores with standard deviations of four English classes are given. Class Mean Standard Deviation Mrs. Jones 89 1 point 9 Mrs. Rijo 82 1 point 4 Mr. Phan 73 3 point 4 Mrs. Scott 90 6 point 1 Which statement is most likely to be true?

Stan guessed on all 10 questions of a multiple-choice quiz. Each question has 4 answer choices. What is the probability that he got at least 2 questions correct? Round the answer to the nearest thousandth. cap p times k successes is equal to n cap c sub k p to the k th power open paren 1 minus p close paren raised to the n minus k power n cap c sub k is equal to the fraction with numerator n factorial and denominator open paren n minus k close paren factorial times k factorial

A convenience sample differs from a voluntary sample in that

Dwayne and Alisha both correctly graphed a standard normal curve. Which of the following statements is true?

Which of the following is a valid probability distribution?

The mean game scores and standard deviations of four seasons of a football team are given. Season Mean Standard Deviation 2005 19 3 point 5 2006 21 2 point 8 2007 12 1 point 0 2008 9 4 point 0 Which statement must be true?

The scores of the students on a standardized test are normally distributed, with a mean of 500 and a standard deviation of 110 What is the probability that a randomly selected student has a score between 350 and 550 ? Use the portion of the standard normal table to help answer the question. z Probability 0 point 0 0 0 point 5 0 0 0 0 point 2 5 0 point 5 9 8 7 0 point 3 5 0 point 6 3 6 8 0 point 4 5 0 point 6 7 3 6 1 point 0 0 0 point 8 4 1 3 1 point 2 6 0 point 8 9 6 1 1 point 3 5 0 point 9 1 1 5 1 point 3 6 0 point 9 1 3 1

A manager records the number of hours, cap x , each employee works on his or her shift and develops the probability distribution. Fifty people work for the manager. How many people work 4 hours per shift? Probability Distribution Hours Worked: cap x Probability: cap p times cap x 3 0 point 1 4 ? 5 0 point 1 4 6 0 point 3 7 0 point 3 6 8 0 point 0 6

Which normal distribution has the greatest standard deviation?

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?

You pick a card at random from an ordinary deck of 52 cards. If the card is a diamond, you get some points; if not, you lose 2 points. What value for the diamonds would make the game fair?

The annual salaries of all employees at a financial company are normally distributed with a mean mu is equal to 34 dollars comma 000 and a standard deviation sigma is equal to 4 dollars comma 000 What is the z - score of a company employee who makes an annual salary of 28 dollars comma 000 ?

Which statement must be true?

Which graph is more likely to show a buyer that it is a good time to buy a car?