Flashcards in deck_1041142 Deck (79):
1. When computing the variance of a sample, the sum of the squared deviations, E (x-x)z, is divided by?A. The population sizeB. The sample size minus oneC. The sample sizeD. The population size minus oneE. None of the above
2. A company wants to graphically summarize in one chart the number of employees it has in each of its five decisions. What type of chart would be appropriate for this purpose?A. Line chart B. Box plot C. Scatter diagram D. Bar chartE. None of the above
3. A manufacturer claims to have built a home stereo speaker that is 4 feet tall but uses an average of only 30 watts of power. A sample of 40 speakers from the manufacturer found that they used an average of 32 watts of power. The appropriate hypotheses to test the manufacturer’s claim are?A. Ho: M=30 versus HA:M=not equal30B. Ho: M=32 versus HA: M=not equal32C. Ho: M=30 versus HA:M=32D. Ho: M=30 versus HA:M>30E. None of the above
4. If the alternative hypothesis states that the population mean is not equal to 3500, the rejection region will consist of?A. One region in the left tail (below 3500)B. One region in the right tail (above 3500)C. Two regions, one in the right tail and one in the left tail.D. One region, centered about 3500.E. None of the above.
5. A 98% confidence interval for a population proportion is determined to be 0.756 to 0.834. If the confidence level is reduced to 95%, the same data will produce an interval that?A. Is widerB. Is narrowerC. Is the sameD. You cannot answer the questions without knowing the sample size.E. None of the above.
6. If the correlation coefficient, r, is equal to one?A. The y-intercept must be equal to zeroB. The regression line goes through all the points and has a negative slope.C. The standard error of the estimate, Sz is zero.D. The slope of the regression line is one.E. None of the above.
7. The expected value of a random variable is also?A. The median.B. The modeC. A weighted average D. The varianceE. None of the above
8. A study if elementary schools in the Los Angeles Unified School District focused on the percentage of teachers in each school with emergency credentials (x, in percent) and the average reading scores (y) of fourth grade students in that school. The least squares regression line was y=400-3x. If twenty percent of the teachers in prairie Elementary in the San Fernando Valley have emergency credentials, you would expect the average reading scores of the fourth grade students in prairie Elementary to be?A. 60B. 100C. 340D. 399.4E. None of the above
9. Ten percent of the mail that arrives at a post office has insufficient postage attached. If a postal worker selects 15 pieces of mail at random, what probability distribution should he use to calculate the probability that three pieces of mail have sufficient postage?A. PoissonB. Exponential C. Normal D. UniformE. None of the above
10. If the population is normal, the population standard deviation is known, and the sample size is ten, which table would you use for calculating probability of the sample mean?A. Normal B. Student tC. Chi-squareD. BinomialE. None of the above
11. If the null hypothesis is that the population mean is equal to 30 and you conduct a test with a significance level of 0.05 and get a p-value of 0.08, then?A. You must reject the null hypothesisB. You are certain that the population mean is 30.C. You cannot reject the null hypothesis.D. The probability of type II error is 0.08E. None of the above.
12. A researcher has taken a random sample of more than two items. Compared with the population standard deviation, the standard error of the mean is?A. Larger than the population standard deviation.B. Smaller than the population standard deviation.C. The same as the population standard deviation.D. Sometimes larger and sometimes smaller than the population standard deviation.E. None of the above.
13. A manufacturer of children’s toys claims that exactly 5% of all his producing are defective. When 500 toys from today’s outputs were examined 0.8% were found to be defective. The 500 toys is?A. The parameterB. The statisticC. The populationD. The sampleE. None of the above.
14. A researchers is studying registered voters in Los Angeles to see if they favor the city of Los Angeles being divided into boroughs (smaller governmental units within the structure of the city). He asks 350 voters to tell him if they would vote for a plan that would implement a borough system in Los Angeles. Out of the 350, 235 said they were in favor of the plan. The population is?A. The 235 voters in favor of the borough plan.B. The 350 votersC. All the voters in favor of the borough plan.D. All the voters in Los AngelesE. None of the above.
15. A market researcher has interviewed 80 heads of house holds and recorded whether the person was never married, divorced, windowed, or married. The data is?A. DiscreteB. ContinuousC. QualitativeD. Binomial E. None of the above
16. A car dealer is studying his customers and the cars they buy. It is appropriate for him to use a mean to describe?A. The color of the car bought by a typical customer.B. The zip code of a typical customer.C. The mileage in miles per gallon of the car bought by a typical customerD. The city of residence of the typical residence.E. None of the above.
17. Given that a sample of 25 had E x=75, and E (x-x) squared =448, the mean and standard deviation are?A. x=3.0 and s=48/25B. x=3.0 and s=48/24C. x=3.0 and s=square root of 48/24D. x=3.0 and s=square root of 48/25E. None of the above
18. A sample of dental offices found the numbers of cavities filled in the last week to be as follows: 12, 4, 4, 12, 12, 10. The median number of cavities filled is?A. 8B. 9C. 10 D. 11E. 12
19. Suppose that, in testing situation with a population that is normally distributed, the null hypothesis is that the population mean is equal to 41. A sample of size 36 had a sample mean of 41 and sample standard deviation of 2. which of the following is correct?A. You should reject the null hypothesis B. You are certain the population mean is 41C. You cannot reject the null hypothesis D. You must know the population standard deviation to complete the test E. None of the above
20. Which of the following is ALWAYS true for test of hypothesis?A. The null hypothesis contains
21. A sample of 100 receipts from a restaurant showed that 12 had errors. What is the 95% confidence interval for the proportion of all receipts that have error? Note that 20.025= 1.96 and t 0.025= 1.984 for 99 degrees of freedom?A. 0.12 +- (1.96) square root of (0.12)(0.88)/100B. 0.12 +- (1.984) square root of (0.12)(0.88)/100C. 0.88 +- (1.96) square root of (0.12)(0.88)/100D. 0.12+-(1.96) square root of (0.12)(0.5)/100E. None of the above
22. If you have data on product output and total cost of production, you can estimate fixed and variable cost by using?A. Bayes ruleB. Linear regressionC. A hypothesis testD. A confidence intervalE. None of the above
23. The postal service has recently raised the price of a first class stamp by three cents to 37 cents. While you were in the post office, you saw 30 three cent stamps sold and 20 of the new 37 cents stamps sold. What was the average price paid for a stamp while you were in the post office?A. 8.3 centsB. 16.6 centsC. 20 centsD. 25 centsE. none of the above
24. An investor has purchased stock in a firm. The investor believes that , at the end of the year, there is 0.10 probability that the stock will show a $6,000 profit, a 0.30 probability that the stock will show a $4000 profit and a 0.60 probability that the stock will show a $2000 loss. The expected profit is $600. If the best profit increases by $1000 from $6000 to $7000, the expected profit?A. Will remain unchangedB. Will increase by $10C. Will increase by $100D. Will increase by a $1000E. None of the above
25. The number of hours in the life time of a light bulb is a random variable of which type?A. BinomialB. PoisonC. ContinuosD. DiscreteE. None of the above
26. Which of the following in NOT an assumption that is required for the use of the binomial formula?A. The trial are independentB. The probability of success is the same for every trialC. Each trial has only two possible outcomesD. The random variable is the number of success out of N trialsE All of the above assumptions are required
27.A survey was conducted in July, 2002 of 200 of the 6000 CSUN business students. The survey asked the questions: Are you taking BUS 301 in the fall? Twenty percent of the 200 students said yes. Using this information?A. The college knew exactly how many sections of BUS 301 to scheduleB. The College knew exactly how many how many sections of bus301 to schedule, but didn’t know how many should be at nightC. The college knew the maximum number of section of bus 301 necessaryD. The college didn’t have enough information to be sure of hoe many sections to scheduleE. None of the above
28. If a television rating service surveyed 800 viewers and 700 watched American Idol, the population is?A. The 800 viewers surveyedB. The 700 viewers who watched American idol C. The 100 viewers who did not watch American idol D. All television viewersE. None of the above
29. You survey your friends and ask them which type of movie (action, comedy, romance, horror) they prefer. Which of the following graphical displays would be most appropriate to display the data?A. Scatter diagramB. A least squares regression lineC. A box plotD. A bar chartE. None of the above
30. A car manufacturer states on the window sticker of its new cars: 38 MPG Highway. This is an example of?A. A meanB. A proportion C. A standard deviationD. A rangeE. None of the above
(1) A study of the number of cars sold looked at the number of cars sold at 500Dealers The smallest dealer had 11 cars sold and the largest had 154 cars sold. If you were going to create a frequency distribution of the number of cars sold using six classes in your frequency distribution, which of the following might be a reasonable first class?
(a) 0 to 25
(3) Which of the following is always true for a test of a hypothesis? (a) The type ll error is more important than type l error (b) is larger then (c ) is the probability of a type ll error (d) A type l error occurs when you accept the null hypothesis when it is not true (e) None of the above is true
(4) Suppose that, in attesting situation with a population that is normally distributed,The null hypothesis is that the population mean is equal to 41. A sample of size 36 had a sample mean of 41 and sample standard deviation of 2. Which of the following is correct?
(b) You cannot reject the null hypothesis
(5) If you take a sample of size 24 from a normal population for which you do not know the population standard deviation and want to calculate a 95% confidence interval for the mean, which is not need?
(c) The value of Z0.025
(6) The coefficient of determination, R²
(b) Tell us how close the Regression line fits the points in a scatter diagram.
(7) The expected value of a random variable is also
(c) A weighted average
(8) The retail price of a product is $5 per unit & the cost of production is $2 per unit. If the expected number of unit sold is 4, the expected profit will be
(b) 12 ($5 profit per unit - $2 cost per unit = $3 * 4 unit sold = 12)
) Is not assumption that is required for the use of binomial formula? (a) The trails are independent (b) The probability of success is the same for ever trail. (c) Each trail has only 2 possible outcomes (d) The random variable is the number of successes out of a trails (e) All of the above.
You are measuring the life time of a light bulb. Which of the following might bethe distribution of this random variable? (a) Binomial (b) Normal (c) Poisson (d) All three (e) None
(11) If the P value is less then Alpha, you
(c ) Should reject the null hypothesis.
(12) Because of the variation in the measured contents of a can of cola,
(b) The average contents of a sample of 10 cans will give us the average contents for the day’s production of 100,000 cans.
A manufacturer of children’s toy claims that exactly 5% of all his products are defective. When 500 toys from today’s output were examined, 8% were found to be defective. What is the parameter?
(b) The % of all the toys made that are defective.
X claims that the average box of X contains 12 ounces. You bought 1 box at each 5 different grocery stores. The weights were 13.1, 11.6, 12.1, 12.3 & 11.9 ounces. The mean weight of the 5 boxes was 12.2 ounces. The sample is -- (5)
E None of the above
(15) A car manufacturer is studying the relationship between the weight of its vehicles and the mileage they get in city driving. Which following would an analyst for the company construct to aid in this study?
(b) The least squares regression line.
Which of the following is NOT quantitative date?
(c ) Whether a driver buys premium gasoline or not
A basketball player scored 12, 25, 16, & 13 points in her last 4 games. What is the mean number of points per game she scored during this period?
The sample 10, 18, 20 has a standard deviation of
(b) 5.29 [(36+4+16) ÷ 2] = 56 ÷ 2 = √28 = 5.29
Which of the following is NOT one of the steps in hypothesis testing?
- Calculate the sample Z-value (test statistic)
(20) An urban planner wished to determine whether there is sufficient evidence to conclude that the mean family income in the San Fernando Valley exceeds $38000. When the urban planner collects data on family incomes, he would –
(a) Use a one-tailed test with the alternative to the right (above $38000)
A study was conducted in Malibu on the value of a house (Y, in thousands of dollars) as it relates to the distance the house is from the beach (X, in miles). The result was the regression equation, Y= 800-20X. In the equation, the number 20 represents.
(c) For each extra mile a house is from the beach, the price drops by $20,000
The probability distribution of Z is: X 1, 2, 3, 4 P(X) .30, .35, .20, .15 What is the expected number of children in a randomly selected Canadian household? Let X represent the number of children in Canadian household.
) A sales representative make 3 in person visits to customers every morning. Out of the 3 visits, she will make either 0, 1.3 or 3 sales. The probabilities are 0.2, 0.4, 0.3, and 0.1, respectively. For each sale, she gets a commission of $100. Her expected commissions for one morning’s visits are...
The binomial distribution is a distribution.(a) Which is always symmetric(b) Can always be used when sampling without replacement(c) Which always takes integer values(d) Which is always more spread out than the normal distribution(e) None
A random variable is found by sampling classes at CSUN and counting the number of those classes with over 200 students enrolled. Which of the following distributions might be the distribution of this random variable.
For a given hypothesis test, the null hypothesis can be rejected at the 0.05 level of significance. We can infer that P-value.
(a) Is less than 0.05
When you increase the size of your sample from a population, (a)You decrease the population standard deviation (b) You increase the standard deviation of the sample mean (c) You decrease the standard deviation of the sample mean (d) You decrease the sample standard deviation (e) None
A summary measure computed from a sample is a
A manufacturer of children’s toys claims that exactly 5% of all his products are defective. When 500 toys from today’s output were examined, 8% were found to be defective. What is the sample?
A student took a sample of 25 textbooks from the bookstore and recorded the costs of the books. The student wants to know whether the mean cost of all textbooks is greater than $75. The student should,
(e) Test the null hypothesis that the mean cost of all textbooks is equal to $75.
Reasons to calculate the mean of a data set a. find range b. find smaller number c. find middle number d. find measure of location e. None of the above
. Ho: π= .6 H1: π >.6 sample is 250 p=.63 z=.97 sig.=.05 critic. z=1.64 a. reserve null hypothesis b. reject null c. accept alternative d. conclude π> .6 e. none of above
. If alt. hypothesis states pop. Mean= 3500, rejection region will be…
c. left and right region
. There is a .20 probability that stock will profit 3000, .10 prob. That stock will profit 6000, .70 prob. -2000 losses. What is expected profit? a. -200 b. 2333 c. 2600 d. 3667 e. none
Which is NOT characteristic of normal distribution. a. symmetric distribution b. mean is 0 c. mean, median, mode is equal d. distribution is bell shaped e. all of the above
A or B
P value is > α you
Accept Null hypothesis
Summary measure computed from population is a: a. parameter b. stat c. population d. sample e. none
. Sampled 20 banks and recorded rates for 30 yrs. Data is: a. discrete property that the number of possible values is either a finite number or a “countable” number, which results in 0 possibilities, or 1 possibility or 2 possibilities and so on. b. continuous Result from infinitely many possible values that correspond to some continuous scale that covers a range of values without gaps, interruptions or jumps c. qualitative - data that can be separated into different categories distinguished by some nonnumeric characteristic d. binomial is an abstraction of the intuitive concept of chance into the theoretical domains of mathematics, forming the foundations of probability theory and mathematical statistics
Computing variance of sample sum of the square deviation is divided by
- Population size minus one
. Distributing of home prices is often positively skewed (right). Its likely that
- Mean greater than median
Not a step in hypothesis testing
- Calculate the sample Z-value (test statistic)
. Which of the following statement is correct?
- Expected value of a random variable is the long run average assuming the experiment is repeated many times.
The correlation coeffiect “r”
- Measure the relative relationship between 2 variable
Hypothesis test, the null hypothesis can be rejected at the 0.05 level of significance. We can conclude that the p-value
- is less than 0.05
Sample of 20 CSUN students found the age of each student……-
The highest age is at least twice the average age
111) X 0 1 2 P(x) 0.1 0.6 0.3 The expected value of X, E(x) isA. 1.0B. 1.2C. 1.5D. 0.3E. None
115. Which of the following is NOT measure of location or central tendency?A. MeanB. ModeC. Range D. MedianE. None
117. Reason to calculate the meana. Find Range of datab. Find smallest numberc. Find middle numberd. Measure of the location or central trend of numbers in the data sete. None
. The expected value of a random variable is the long run average value assuming the experiment is repeated many times T/F