stats practice final exam
How would you find the mean of data from cells B1 to B10 in Excel? a) = AVERAGE(B1:B10) b) = AVG(B1:B10) c) = MEAN(B1 - B10) d) = MEAN(B1:B10) e) = MEAN.S(B1:B10)
a)
Given a T distribution with the degrees of freedom of 16. Which function finds the probability that T is greater than 1.4? a) =1- T.DIST(1.4, 15, TRUE) b) =1-T.DIST(1.4, 16, TRUE) c) =T.DIST(1.4 0, 1, TRUE) d) = T.DIST(1.4, 16, TRUE) e) =T.DIST(1 - 1.4, 16, TRUE)
b)
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?
d)
A diabetic claims that the average cost of insulin per year for a Type 1 diabetic is $5,605. She takes a sample of 100 Type 1 diabetics and finds their average cost is $5, 750 with a standard deviation of $370. Use α=0.05to test the claim. What are the hypotheses?
a)
A sociologist wishes to test H0:μ≤42 vs. Ha:μ>42. The sociologist takes a sample of size 100 and calculates a standardized test statistic of 2.34. To calculate a p-value for the test in Excel, the sociologist should use: a) =1-NORM.DIST(2.34, 0, 1, TRUE) b) =1-T.DIST(2.34, 99, TRUE) c) =NORM.DIST(2.34, 0, 1, TRUE) d) =2*NORM.DIST(2.34, 0, 1, TRUE) e) =T.DIST(2.34, 99, TRUE)
a)
The level of significance (α) is _______________. a) the maximum probability of making a Type I error b) the maximum probability of making a Type II error c) the maximum allowable probability of getting results as extreme as the actual observed values. d) when a result is very unlikely to have happened given the null hypothesis.
a)
The mean score on a standardized math exam is 75; the standard deviation is 8. Zack is told that the z-score of his exam score is -1.25. Which of the following statements is true? a) Zack's score is below the class average. b) Zack's score is above the class average. c) More information is needed to decide whether Zack's score is below or above the class average.
a)
You roll a fair six-sided die. Find the probability of event A: rolling an even number. a) P(A) = 3/6 b) P(A) = 2/6 c) P(A) = 1/6 d) P(A) = 4/6 e) P(A) = 5/6
a)
A survey shows that people use cell phones an average of 1.6 years with a standard deviation of 0.3 years. A user is randomly selected. If cell phone use is normally distributed, we can use Excel to calculate the probability that the randomly selected user uses their phone for more than 1 year with the function: a) =NORM.DIST(1, 1.6, 0.3, TRUE) b) =1 - NORM.DIST(1, 1.6, 0.3, TRUE) c) =NORM.DIST(1, 1.6, 0.3, FALSE) d) =1 - NORM.INV(1, 1.6, 0.3) e) =NORM.INV(1, 1.6, 0.3)
b)
If H0: p≥0.80, then the test will be ___________. a) Two-tailed b) Unable to tell given the current information c) Right-tailed d) Left-tailed
b)
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 equation should he use to construct the 95% confidence interval for the true proportion of all people who voted?
b)
In the test of hypotheses H0:μ≥100 vs Ha:μ<100 . A sample of size 81 yields the standardized test statistic −1.50 . Which function in Excel finds the p-value? a) =1-T.DIST(-1.50, 80, TRUE) b) =NORM.DIST(-1.50, 0,1,TRUE) c) =NORM.INV(-1.50, 0, 1) d) =1-NORM.DIST(-1.50, 0,1,TRUE) e) = T.DIST(-1.50, 80, TRUE)
b)
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 0.05? a) The information is not enough to make a decision. b) Reject H0 since the P-value is less than the significance level. c) Fail to reject H0 since the P-value is greater than 0.01. d) Fail to reject H0 since the P-value is less than the significance level. e) Reject H0 since the P-value is greater than 0.01.
b)
Let x be a discrete random variable with the following probability distribution: Find P(x>1) a) 0.2 b) 0.4 c) 0.3 d) 0.7 e) 1.0
b)
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: a) All college students who have off-campus jobs. b) All college students. c) The 451 students in the survey who had off-campus jobs. d) All 1600 students surveyed.
b)
The average sales price of single-family houses in Charlotte is $350,000 with a standarddeviation of $40,000. A random sample of 100 single-family houses in Charlotte isselected. Let x¯ represent the mean sales price of the sample. What is the mean of the sampling distribution of x¯, i.e., μx¯? a) 6.4 b) 350,000 c) 40,000 d) 35,000 e) 64
b)
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 Republican party; B be the event that the selected person is a Male. Find (A U B) a) 0.45 b) 0.85 c) 0.15 d) 0.60 e) 0.40
b)
The probability distribution of a discrete random variable X is given by Find the missing probability in the table. a) 0.40 b) 0.30 c) 0.20 d) 0.50 e) 0.10
b)
A government agency was charged by the legislature with estimating the length of time it takes citizens to fill out various forms. The agency generated an 85% confidence interval, a 90% confidence interval, and a 99% confidence interval, all of which are listed below. Which one is the 99% confidence interval? a) (12.63, 12.97) b) (12.60, 13.00) c) (12.49, 13.11)
c)
A nutritionist claims that the average amount of sugar in a 16 oz soda is at least 50 g. He randomly samples 10 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 α=0.10to test the claim. In this scenario, the appropriate test statistic is:
c)
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. In this sample, how many students are taking between 3 to 12 credits, inclusive? a) 19 b) 6 c) 11 d) 5 e) 21
c)
If everything else remains the same which of the following confidence level will result the widest confidence interval? a) 95% b) 80% c) 99% d) 97% e) 90%
c)
In a random sample of 14 people, the mean body mass index (BMI) was 25.7 and the standard deviation was 5.12. Assume the body mass indexes are normally distributed. Which equation should he use to construct a confidence interval for the population mean BMI?
c)
In the past, it is generally agreed that a certain standard treatment yields a mean survival period of 5.2 years for certain cancer patients. Recently, a new treatment is administered to 64 patients and their duration of survival is recorded. The sample mean and standard deviation of the duration is 5.8 years and 0.6 years, respectively. Set up the null and alternative hypotheses to test whether the new treatment increases the mean survival period. a) H0:μ>5.2;Ha:μ≤5.2. b) H0:μ≥5.2;Ha:μ<5.2. c) H0:μ≤5.2;Ha:μ>5.2 d) H0:μ≤5.8;Ha:μ>5.8
c)
Let X be the number you observe when you randomly roll a fair 6-sided die. An experiment consists of taking 1000 such rolls (i.e., sample size n = 1000). Let X¯be the average value of these 1000 rolls. Does X¯ follow approximately a normal distribution? a) It really depends on the population distribution. b) False c) True
c)
The score made by a particular student on a national standardized exam is the 75th percentile. This means that a) He got about 75% of the answers correct. b) About 75% of all scores on the exam were higher than his. c) About 75% of all scores on the exam were equal to or less than his. d) His score is 75% of the average score.
c)
The standard deviation of a data set measures the ___________ of the dataset. center a) size b) position c) variability d) most frequent value e) center
c)
There were 1000 students who took part in the common final exam on STAT 1222. The average is 70 with a standard deviation 8. If a student got a z-score of 3.10 in this exam, which of the following is true? a) This student is way below the class average. b) This student is just around the average. c) Compared with other students in this exam, this student did extremely well. d) There is no way to tell about the performance of this student. e) Compared with other students in this exam, this student didn't do well.
c)
Which of the following statements are true about the sampling distribution of x¯? I. The mean of the sampling distribution is equal to the mean of the population. II. The standard deviation of the sampling distribution is equal to the standard deviation of the population. III. The shape of the sampling distribution is always approximately normal. a) I and II only b) I, II and III c) I only d) I and III only e) II and III only
c)
If A = {3, 6, 9, 10} and B = {3, 4, 5, 6}, what is A ∪ B? a) {3,6,9,10,3,4,5,6} b) {3,6,9} c) {4,5,9,10} d) {3,4,5,6,9,10} e) {3,6}
d)
In a situation of hypothesis testing, what happens when the null hypothesis H0is wrongly rejected when it is actually true? The Type I error probability is 0.5 or 50%. a) A Type II error occurs. b) The Type II error probability is 0.5 or 50%. c) The Type I error probability is 0 or 0%. d) A Type I error occurs.
d)
The following table gives the probabilities of all parts made from two production lines at a factory whether they are good or defective . A part is randomly selected from this factory. The probability that this part is defective is about a) 0.58 b) 0.08 c) 0.42 d) 0.10 e) 0.90
d)
A survey was conducted to estimate the proportion of all eligible voters who actually voted in the previous presidential election. The survey investigated 2000 eligible voters and found that 1360 or 68% of them actually voted. Which of the following is true? a) The population in this question consists of 2000 eligible voters. b) The true proportion of all eligible voters who actually voted in the previous presidential election is 0.68. c) The sample is the 1360 eligible voters who actually voted in the previous presidential election. d) The sample size is 1360. e) The sample size is 2000.
e)
Let Z be the random variable which has the standard normal distribution. Which of the following is NOT a property of the the standard normal distribution? a) symmetric about the mean. b) centered at 0 with standard deviation of 1. c) the total area under the curve is equal to 1. d) bell-shaped e) The potential values of Z are from −3 to 3
e)
The probability distribution of a discrete random variable X is given by
e)
Using Excel, how would you find the standard deviation for a sample of data located in cells A1 to A10 ? a) = STANDDEV(A1:A10) b) = STANDDEV.S(A1:A10) c) = STDEV(A1:A10) d) = STDEV.P(A1:A10) e) = STDEV.S(A1:A10)
e)
Which tables give valid probability distribution for a discrete random variable? a) I, II and III b) I only c) IV only d) III and IV e) I and IV
e)