Canvas Review Test 1

These are 85%, 90% and 99% confidence interval, all of which are listed below. Which one is the 99% confidence interval?

(12.49, 13.11)

For a 95% confidence interval, a= ___ and a/2= ___

0.05; 0.025

Let x be a discrete random variable with the following probability distribution: x: 2, 0, 1, 2, 9 P(x): 0.1, 0.3, 0.3, 0.1, 0.2 Find P(x>2)

0.2

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. Vote for Democratic Party/Vote for Republican Party Male: 0.15, 0.25 Female: 0.40, 0.20 Let A be the event that the selected person will vote for Democratic party; B be the event that the selected person is a Male. Find P(A∪B)

0.80

If sample size does not change, and mean and standard deviation still same, which of the following confidence level will result the widest confidence interval?

99%

How would you find the mean of data in the range B2 to B42 in Excel?

= AVERAGE(B2:B42)

Using Excel, how would you find the standard deviation for a sample of data located in cells A2 to A6 ?

= STDEV.S(A2:A6)

In the test of hypotheses H0: μ ≥ 10 vs Ha: μ< 10. A sample of size 70 yields the standardized test statistic −2.1 . Which function in Excel finds the p-value?

=NORM.DIST(-2.1, 0,1,TRUE)

In a situation of hypothesis testing, what happens when the null hypothesis H0 is wrongly rejected when it is actually true?

A Type I error occurs.

The score made by a particular student on SAT test is the 87th percentile. This means that

About 87% of all scores on the test were equal to or less than his.

The Department of Education wishes to estimate the proportion of all college students who have a job off-campus. It surveyed 2000 randomly selected students; 400 had such jobs. The population of interest to the Department of Education is:

All college students.

The teacher obtained the 95% confidence interval for the average test score is (78.01, 85.45). But he thought this interval is too wide. Which of the following actions will result in a narrower interval?

Construct a 90% confidence interval instead of a 95% one.

In the past, sleeping disorder patient sleep approximately 4.5 hours per day . Recently, a new treatment is administered to 100 patients and their sleep hours are recorded. The sample mean and standard deviation is 6 hours and 0.3 hours, respectively. Set up the null and alternative hypotheses to test whether the new treatment increases the mean sleeping time.

H0: μ ≤ 4.5 Ha: μ > 4.5

Seven bear tracks were found in the woods. Their length was measured in inches and recorded in the table below: 9.25, 9.25, 9.4, 9.5, 9.6, 9.6, 9.6 If another bear track was found that was 7.8 in, what would happen to the mean?

It would decrease.

The mean score on a standardized math exam is 78; the standard deviation is 7. Kyle is told that the z-score of his exam score is -1.36. Which of the following statements is true?

Kyle's score is below the class average.

If H0: p ≥ 0.50, then the test will be ___________.

Left-tailed

You roll a fair six-sided die. Find the probability of event A: rolling an odd number.

P(A) = 3/6

In the test of hypothesis H0: μ=10 vs Ha: μ≠10, we already have the p-value for this test: P-value=0.075. Which of the following (with the reason) will be correct with significance level at 0.1?

Reject H0 since the P-value is less than the significance level.

In a random sample of 25, mean was 12 and the standard deviation was 1.2. Assume the data is normally distributed. Which equation should he use to construct a confidence interval for the population mean

T interval

Let Z be the random variable which has the standard normal distribution N(0,1). Which of the following is NOT a property of the the standard normal distribution?

The potential values of Z are from -3 to 3.

A student takes a set of 30 measurements. The standard deviation is reported as -1.50. Which of the following must be true?

The standard deviation was calculated incorrectly

Let X be the number you observe when you randomly roll a fair 6-sided die. An experiment consists of taking 500 such rolls (i.e., sample size n = 500). Let Xbar be the average value of these 500 rolls. Does Xbar follow approximately a normal distribution?

True

You are tossing a fair coin. Let X=1 if you observe a head and X=0 if you observe a tail. Which of the following tables represents the resulting probability distribution for the random variable X?

X: 0, 1 P(x): 1/2, 1/2

A nutritionist claims that the average amount of sugar in a 16 oz soda is at least 50 g. He randomly samples 70 sodas and finds they contain an average of 54 g of sugar with a standard deviation of 3 g. Assume the population is normally distributed and use a = 0.10 to test the claim. In this scenario, the appropriate test statistic is:

Z = (xbar - μ0) / (s/√n)

Identify the following measures as either quantitative or qualitative: The air pressure of tire quantitative continuous The genders of horse The age (in years) of the monkey The temperature of the last month in 40 different cities The Student ID

quantitative continuous qualitative quantitative discrete quantitative continuous qualitative

What is the proportion of adults who are using cash in store in USA? In a recent survey, 2000 shoppers in the United States were asked if they use cash regularly. 250 of them said yes. Which of the following is true?

sample size is 2000

(I cannot add the image so this is what the graph looks like) (A is right-tailed, B is left-tailed, and C peaks in the middle) Graph (a) is ___ and therefore we expect that the mean is ___ the median. Graph (b) is ___ and therefore we expect that the mean is ___ the median. Graph (c) is ___ and therefore we expect that the mean is ___ the median.

skewed right; higher than skewed left; lower than symmetric; the same as

The standard deviation and variance of a data set measures the ____of the dataset. Mean, median, and mode are all measures of the ____ of a data set

spread; center

The significance level a = 0.05 means

the maximum probability of making a Type I error is 0.05

If A = {3, 6, 8, 12} and B = {3, 6, 7, 11}, what is A ∪ B?

{3,6,7,8,11,12}

The probability distribution of a discrete random variable X is given by x: 0, 1, 2, 3, 4 p(x): 0.10, 0.30, 0.40, 0.10, 0.10 Which of the following formula will be used to find the mean of the distribution?

μ = Σ x*p(x)