# stats

Cora is playing a game that involves flipping three coins at once. Let the random variable X be the number of coins that land showing "heads". Here is the probability distribution for X:

=0*0.125 + 1*0.375 + 2*0.375 + 3*0.125

The proportions of families with various numbers of children age 18 or under in a small town are given in the following table. One family is randomly selected from this town. Find the probability that the selected family has at least 1 children age 18 or under.

0.90

If every else remain the same which of the following confidence level will result the narrowest confidence interval?

80%

If every else remain the same which of the following confidence level will result the narrowest confidence interval?

85%

The probability that this part is defective or is made from production line 2 is about

=(13+90-8)/160

The following two-way contingency table gives the breakdown of the voters in a particular locale according to gender and political party preference. A person is selected at random from this population. Let A be the event that the selected person will vote for the Republican party; B be the event that the selected person is a female. Find the probability that the selected person is a Republican or a female.

=(470+480-190)/1000

A construction company is considering submitting bids for two contracts. It will cost the company $10,000 to prepare and submit the bids, and if won, each bid would produce $50,000 income for the company. The company estimates that it has a 10% chance of winning any given bid. Here is the probability distribution of X = the amount of money the company profits from the bids.

=-10000*0.7 + 40000*0.18 + 90000*0.12

A construction company is considering submitting bids for two contracts. It will cost the company $10,000 to prepare and submit the bids, and if won, each bid would produce $50,000 income for the company. The company estimates that it has a 10% chance of winning any given bid. Here is the probability distribution of x = the amount of money the company profits from the bids.

=-10000*0.7 + 40000*0.18 + 90000*0.12

The following two-way contingency table gives the breakdown of the population in a particular locale according to party affiliation (A, B, C, or None) and opinion on a bond issue: A person is selected at random. The probability that the person has no party affiliation is ______________.

=0.08 + 0.06 + 0.03

The following two-way contingency table gives the breakdown of the population in a particular locale according to party affiliation (A, B, C, or None) and opinion on a bond issue: A person is selected at random. The probability that the person has no party affiliation OR is undecided is.

=0.17+0.30-0.03 .

Let Z be the standard normal random variable. Find p(z>0.72)

=1 - NORM.DIST(0.72, 0, 1, TRUE)

An inspection of 160 parts made from two production lines at a factory yields the following table. A part is randomly selected from these 160 parts. The probability that this part is good is about ________.

=147/160

The table shows the results of a survey in which 90 dog owners were asked how much they have spent in the last year for their dog's health care, and whether their dogs were purebred or mixed breeds. Find the probability that a randomly selected dog owner spent at least $100 on health care and the dog was a mixed breed.

=15/90

The manager of the dairy section of a large supermarket chose a random sample of 250 egg cartons and found that 30 cartons had at least one broken egg. let p denote the proportion of all cartons which have at least one broken egg. Which of the following calculates the point estimate for p and also the critical value for the 90% confidence interval for p?

=30/250 and =NORM.INV(1-0.10/2, 0, 1)

Given that a randomly selected dog owner spent at least $100, find the probability that the dog was a Purebred. (i.e. Among the dog owners who spent at least $100, what's the likelihood that the dog was a purebred)

=35/50

The table shows the results of a survey in which 90 dog owners were asked how much they have spent in the last year for their dog's health care, and whether their dogs were purebred or mixed breeds. Given that a randomly selected dog is purebred, find the probability that the dog owner spent at least $100 on healthcare. (i.e. Among the dogs who are purebred, what's the likelihood that the dog owner spent at least $100)

=35/54

You are taking a multiple-choice quiz that consists of four questions. Each question had five possible answers, only one of which is correct. To complete the quiz, you randomly guess the answer to each question. Which of the following shows the correct EXCEL formula to compute the probability of guessing less than three answers correctly.

=BINOM.DIST(2, 4, 0.2, TRUE)

You are taking a multiple-choice quiz that consists of five questions. Each question had four possible answers, only one of which is correct. To complete the quiz, you randomly guess the answer to each question. Which of the following shows the correct EXCEL formula to compute the probability of guessing less than three answers correctly.

=BINOM.DIST(2, 5, 0.25, TRUE)

A city government asks 500 randomly selected people whether or not they are employed. The population percentage of employment is 0.60. Which equation would calculate the probability that exactly 250 of these people are employed?

=BINOM.DIST(250, 500, 0.60, FALSE)

You are taking a multiple-choice quiz that consists of twenty questions. Each question had six possible answers, only one of which is correct. To complete the quiz, you randomly guess the answer to each question. Which of the following shows the correct EXCEL formula to compute the probability of guessing less than five answers correctly.

=BINOM.DIST(4, 20, 1/6, TRUE)

In a study of the amounts of time required for room service delivery at a newly opened Radisson Hotel, 45 deliveries had a mean time of 24.2 min and a standard deviation of 8.7 min. Which of the following calculates the margin of error (EBM) for the 90% confidence interval for the mean of all deliveries?

=CONFIDENCE.NORM(0.10, 8.7, 45)

The length a wild of lemur's tail has a normal distribution with a mean of 1.95 feet with a standard deviation of 0.2 feet. What is the probability that a randomly selected lemur has a tail shorter than 1.7 feet?

=NORM.DIST(1.7, 1.95, 0.2, TRUE)

The length of a wild lemur's tail has a normal distribution with a mean of 1.95 feet with a standard deviation of 0.2 feet. A random sample of 64 lemurs is selected. Calculate the probability that the average of their tail lengths is between 1.9 and 2.11 feet.

=NORM.DIST(2.11, 1.95, 0.2/SQRT(64), TRUE) - NORM.DIST(1.9, 1.95, 0.2/SQRT(64), TRUE)

The amount of time spent by individuals completing Form 1040 Schedule U of U. S. tax returns is normally distributed with mean 73 minutes and standard deviation 12 minutes. Suppose 10 randomly selected people are timed completing Schedule U. Find the probability that the mean time to complete the form will be between 70 and 75 minutes.

=NORM.DIST(75, 73, 12/SQRT(10), TRUE) - NORM.DIST(70, 73, 12/SQRT(10), TRUE)

The length a wild of lemur's tail has a normal distribution with a mean of 1.95 feet with a standard deviation of 0.2 feet. Which of the following shows the correct EXCEL formula to calculate the 67th percentile of lemur tail length.

=NORM.INV(0.67, 1.95, 0.2)

Scores on the common final exam in the Elementary Statistics course are normally distributed with a mean of 75 and a standard deviation of 10. The department has the rule that in order to receive an A in the course his score must be in the top 25% of all exam scores. Which of the following shows the correct EXCEL formula to calculate the minimum IQ score required by this program?

=NORM.INV(0.75, 75, 10)

Consider the three normally distributed random variables A, B, and C, pictured below. Which of the following is a true statement?

All 3 have the same mean, and A has the smallest standard deviation.

In a survey of 1000 people, 700 people said that they voted in the last presidential election. Let p denote the proportion of all people who voted. Which of the following actions would result in a confidence interval wider than the 99% confidence interval computed from this sample?

Decreasing the sample size

An inspection of 160 parts made from two production lines at a factory yields the following table. A part is randomly selected from these 160 parts.

Given that a randomly selected part is from production line 1, find the probability that it is defective.

The accompanying data represent the total travel tax (in dollars) for a 3-day business trip in 8 randomly selected cities. Supposed that the data come from a population that is normally distributed. 68.69, 79.99, 69.99, 83.01, 79.43, 87.28, 100.71, 99.69 Based on this sample, the mean is $83.60. Suppose an accountant calculated the 95% confidence interval for the mean tax paid for a three-day business trip, and he got 73.59 for the lower bound and 93.61 for the upper bound. What does this mean?

One can be 95% confident that the mean travel tax for all cities is between $73.59.and $93.61.

A survey was conducted that asked 1012 people how many books they had read in the past year. Results indicated that xbar = 11.5 books and s = 16.6 books. A researcher calculated the 95% confidence interval for the mean number of books people read and she got 10.48 for the lower bound and 12.52 for the upper bound. Interpret the interval.

There is 95% confidence that the population mean number of books read is between 10.48 and 12.52.

The average sales price of single-family houses in Mooresville is $215,000 with a standard deviation of $45,000. A random sample of 60 single-family houses in Mooresville is selected. Let X¯ represent the mean sales price of the sample. Find the mean and standard deviation of X¯.

mean = 215000, stdev= 45000/sqrt(60)

The average sales price of single-family houses in Mooresville is $345,000 with a standard deviation of $15,000. A random sample of 80 single-family houses in Mooresville is selected. Let x¯ represent the mean sales price of the sample. Find the mean and standard deviation of x¯

mean = 345000 stdev - 15000/sqrt(80)

A survey in a community states that 250 out of 750 people smoke on a regular basis. Using the information from this survey, a researcher wishes to estimate the required sample size. He wants to be 87% confident and wants the sample proportion to be within 1.5% of the population proportion. Which of the following is correct?

p' = 250/750; q' = 500/750; EBP = 0.015

A survey in a community states that 430 out of 750 people smoke on a regular basis. Using the information from this survey, a researcher wishes to estimate the required sample size. He wants to be 97% confident and wants the sample proportion to be within 2.5% of the population proportion. Which of the following is correct?

p' = 430/750; q' = 1- 430/750; EBP = 0.025

Which of the following random variables is continuous?

the weight of a baby giraffev