STAT PRACTICE FINAL EAM

A physician wanted to estimate the mean length of time that a patient had to wait to see him after arriving at the office. A random sample of 64 patients showed a mean waiting time of 30 minutes and a standard deviation of 10 minutes. The 95% confidence interval for the mean waiting time is closest to

(27.55, 32.45)

What is the z-score of a person whose LDL is one standard deviation above the mean?

1.0

How would you type the equation "eight divided by six" in Excel?

=8/6

An observation that is radically different from the rest is called

an outlier

Is temperature in oC nominal, ordinal, interval, or ratio?

interval

hair color

nominal

The genders of the first 40 newborns in a hospital one year qualitative

qualitative

distance

ratio

In an exam for a statistics class, the class average is 72 with a standard deviation 4.8. If a student scored 66, which of the following is his z-score in this class?

-1.25

During a test, the class average is 80 with a standard deviation of 4. Linda is told that the z-score of her exam score is -2.50. Find Linda's actual score in this test.

70

A mechanic is interested in when transmissions fail. She randomly selects eleven cars whose transmissions have failed. Ten of them had their transmissions fail between 150,000 to 200,000 miles. The single Chevy Spark examined, however, had its transmission fail at 10,000 miles. How will the mean compare to the median?

Mean < Median

Which of the following statistics is least impacted by outliers?

Median

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. The 90% confidence interval for p is closest to

NOT (0.067, 0.173)

temperature in celcius

interval

Last Wednesday, a random sample of 16 students were surveyed to find how long ittakes to walk from the Fretwell building to the College of Education building. Thesurvey team found a sample mean of 10 minutes with a standard deviation of 1.6 minutes. Assuming walking times from Fretwell to the College of Education are normally distributed, Which of the following is a 90% confidence interval for the population mean of walking times? (round to two decimal numbers)

(9.30, 10.70)

In order to test hypotheses H0: μ=70;Ha: μ<70. A random sample of size 64 is taken . The sample yields x¯=68; s=6. The test statistic is about

-2.67

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. X012345P(X)0.10.40.30.10.050.05 Find the probability that the selected family has at most 1 children age 18 or under.

.50

In the test of hypothesis H0:μ=100vs Ha:μ≠100. A sample of size 100 yields the standard test statistic z=2.50. Find the P-value for this test.

0.0124

A researcher wants to study how sleep deprived college students are. She randomly selects 50 students from a local college and asks them how many hours of sleep they get on a typical night. Her results are shown in the table below. How many students get at least 8 hours of sleep a night?

0.28

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 PartyVote for Republican PartytotalMale240280520Female290190480total5304701000 Find the probability that a randomly selected person will vote for the Republican party and the selected person is a male.

0.28

Let Z be the standard normal random variable. Find P(Z>0.50)

0.3085

An inspection on 160 parts made from two production lines at a factory yields the following table. A part is randomly selected from these 160 parts. Line 1Line 2totalGood 6582147Defective5813total7090160 The probability that this part is made from Line 2 is about

0.56

Assume that children's IQs (Age 6-12) follow a normal distribution with mean 100 and standard deviation of 12. Find the probability that a randomly selected child has IQ above 91.

0.7734

Consider the sample data: 125, 115, 112, 127, 112, 105. What is the sample mean of the data?

116

Consider the sample data: 110, 115, 120, 127, 130, 105. What is the sample median of the data?

117.5

Assume checked airline luggage is normally distributed with a mean of 44.76 pounds and a standard deviation of 14.22 pounds. Out of a sample of 473 bags, how many would you expect would NOT weigh between 35.37 pounds and 60.83 pounds?

182 bags

You are running a political campaign and wish to construct a 99% confidence interval to estimate the true proportion of registered voters who will vote for your candidate. You will conduct a survey and will assume the margin of error E = .03. The minimum sample size required in this survey is

1842

A university dean wants to know how many credits students are taking. They randomly sample some students and put the results in the histogram below. How many students were sampled?

19

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 90th percentile of lemur tail length?

2.21 feet

In a random sample of 200 adults, 136 say they are in favor of outlawing cigarettes in certain areas. Let p be the proportion of all adults who are in favor of outlawing cigarettes. One is interested for the following hypotheses: H0: p=0.6 vs Ha: p>0.6 The standardized test statistics is about

2.31

The average sales price of single-family houses in Charlotte is $210,000 with a standard deviation of $35,000. A random sample of 49 single-family houses in Charlotte is selected. Let x¯ represent the mean sales price of the sample. Find the mean and standard deviation of x¯, i.e., μx¯ and σx¯:

210000 and 5000 respectively.

Consider the sample data: 110, 115, 112, 127, 112, 130. The sample standard deviation is about

8.59

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

80% or the lowest percentage

The length of human pregnancies from conception to birth follows a distribution with mean 266 days and a standard deviation 15 days. Assume the distribution is bell-shaped (symmetric). The percent of pregnancies last between 236 and 281 days is approximately

81.5%

Using Excel, how would you find the standard deviation for a sample of student's GPAs located in cells B1 to B10 ?

= STDEV.S (B1 : B10)

A professor wants to study the GPAs of students enrolled in all STAT 1222 classes at her university. She asks 15 randomly selected STAT 1222 students what their GPA is and finds the average is 3.65. What is the population?A. All STAT 1222 students anywhereB. Students enrolled at her universityC. All students enrolled in STATD. 1222 classes at her universityE. The 15 randomly selected students

C. All students enrolled in STATD.

When is the mode most useful?

Categorical data

In the test of hypothesis H0:μ=100 vs . Ha:μ≠100, we already have the P-value for this test: P-value=0.025. Which of the following (with the reason) will be correct with significance level at .01?

Fail to reject H0 since the P-value is greater than the significance level .01.

Seven footprints were found at a crime scene. 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 footprint was found that was 12 in, what would happen to the median?

It would increase.

A car company claims that the mileage for its newest model is normally distributed with a mean of 29.3 MPG and a standard deviation of 5.4 MPG. Suppose a sample of 40 cars is taken. What is the approximate probability that the average mileage of the cars in the sample will be over 31 MPG?

NOT 0.3060

Suppose a single student is randomly selected from the 11,098 that are represented in the table below. What is the probability that the student selected will be a Graduate Student (Gu) or major in Mathematics (MAT)? Assume students only have one major.Yr | BIO | CJS | MAT------------------------Fr | 430 | 493 | 817So | 859 | 362 | 807Jr | 931 | 522 | 566Sr | 386 | 884 | 471Gu | 754 | 499 | 503Dr | 649 | 216 | 949

NOT 0.4382

With the current manufacturing process, NASCAR tires last an average of 117 miles. A new manufacturing process using different raw materials was used to produce 28 tires which lasted an average of 131 miles with a standard deviation of 29 miles. Determine the appropriate null and alternative hypotheses that should be used to test to see if average milage of tires produced with the new process is significantly higher than the current process, the test statistic (or calculated statistic) and decision if alpha = 0.005. It's assumed that tire life is approximately normally distributed.

NOT Ho: mu = 117 Ha: mu < 117; test statistic = 2.555; Fail to reject the null

In a survey of 210 U.S. adults, it is found that 145 favor a ban on stem cell research. Set up the null and the alternative hypotheses to test whether there is sufficient evidence that over 63% favor a ban on stem cell research. If alpha is set to 4.0%, should the null hypothesis be rejected?

NOT Ho: p = 0.6300 Ha: p not = 0.6300; p-value = 6.95%; Decision: Reject the null.

What is the mean and standard deviation of the discrete random variable called X_Var shown below?X_Var | Prob------------------2,138 | 0.24593,422 | 0.29135,610 | 0.14518,546 | 0.13669,622 | 0.1811

NOT mean = 5,867.60 standard deviation = 3,210.40

Identify the following as either qualitative, quantitative discrete, or quantitative continuous: Body temperatures in oC

Quantitative continuous

Number of students responding to a survey about their names

Quantitative discrete

A scientist takes a set of 50 measurements. The standard deviation is reported as -2.30. Which of the following must be true?

The standard deviation was calculated incorrectly

The mean score on a standardized math exam is 72.6; the standard deviation is 10.5. Paul is told that the z-score of his exam score is 1.2. Is Paul's score above average or below average? above average

above average

The Department of Education wishes to estimate the proportion of all college students who have a job off-campus. It surveyed 1600 randomly selected students; 451 had such jobs. The population of interest to the Department of Education is:

all college students

military rank

ordinal

The 30 high-temperature readings of the last 30 days quantitative continuous

quantitative continuous

The age (in years) of 20 randomly selected fashion models quantitative discrete

quantitative discrete

A geographer randomly selects twenty points in a county to study the elevation. One point is on a large hill while the other points are near water level. What is the shape of the distribution?

skewed right

A researcher wishes to estimate the average amount spent per person by visitors to a theme park. She takes a random sample of forty visitors and obtains an average of $28 per person. The population of interest is

visitors to the theme park.

Which of the following is the symbol for sample mean?

x bar