BUS 302L Statistics Exam Questions with Correct Answers Graded A+
When computing the variance of a sample, the sum of the squared deviations, E (x-x)z is divided by? -
Answers The sample size minus one
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? - Answers Bar chart
A manufacturer claims to have built a home stereo speaker that is 4 feet tall by 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 claims are? - Answers H0:
M=30 versus HA:M>30
If the alternative hypothesis states that the population mean is not equal to 3500, the rejection region
will consist of? - Answers Two regions, one in the right tail and one in the left tail
A 98% confidence interval for 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? - Answers Is narrower
The correlation coefficient, r, is equal to which one? - Answers The standard error of the estimate, Sz is
zero
The expected value of a random variable is also? - Answers A weighted average
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 20% of the
teachers in Prairies Elementary in the San Fernando Valley have emergency credentials, you would
expect the average reading scores of the 4th grade students in Prairie Elementary to be? - Answers 340
10% 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 be used to calculate the probability
that 3 pieces of mail have sufficient postage? - Answers None of the above
If the population is normal, the population standard deviation is known, and the sample size is 10, which
table would you use for calculating probability of the sample mean? - Answers Normal
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? - Answers You cannot reject the null
hypothesis
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? - Answers Smaller than the population standard
deviation
, 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? - Answers
The sample
A researcher 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 they were in favor of. The population is? - Answers All the voters
in Los Angeles
A market researcher has interviewed 80 heads of households and recorded whether the person was
never married, divorced, widowed, or married. The data is? - Answers Qualitative
A car dealer is studying his customers and the cars they buy. It is appropriate for him to use a mean to
describe? - Answers The mileage in miles per gallon of the car bought by a typical customer
Given that a sample of 25 had E x=75, and E(x-x) squared = 48, the mean and standard deviation are? -
Answers x=3.0 and s=square root of 48/24
A sample of dental offices found the number of cavities filled in the last week to be as follows: 12, 4, 4,
12, 12, 10. The median number of cavities filled is? - Answers 11
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 a sample
standard deviation of 2. Which of the following is correct? - Answers You cannot reject the null
hypothesis
Which of the following is ALWAYS true for test of hypothesis? - Answers None of the above
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 z 0.025 = 1.96 and t 0.025 = 1984 for
99 degrees of freedom. - Answers 0.12+-(1.96) square root of (0.12)(0.88)/100
If you have data on product output and total cost of production, you can estimate fixed and variable cost
by using? - Answers Linear regression
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? - Answers 16.6 cents
An investor has purchased stock in a firm. The investor believes that, and the end of the year, there is
0.10 probabilities that the stock will show a $6,000 profit, a 0.30 probability that the stock will show a
$4,000 profit and a 0.60 probability that the stock will show a $2,000 loss. The expected profit is $600. If
the best profit increases by $1,000 from $6,000 to $7,000, the expected profit? - Answers Will increase
by $100
When computing the variance of a sample, the sum of the squared deviations, E (x-x)z is divided by? -
Answers The sample size minus one
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? - Answers Bar chart
A manufacturer claims to have built a home stereo speaker that is 4 feet tall by 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 claims are? - Answers H0:
M=30 versus HA:M>30
If the alternative hypothesis states that the population mean is not equal to 3500, the rejection region
will consist of? - Answers Two regions, one in the right tail and one in the left tail
A 98% confidence interval for 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? - Answers Is narrower
The correlation coefficient, r, is equal to which one? - Answers The standard error of the estimate, Sz is
zero
The expected value of a random variable is also? - Answers A weighted average
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 20% of the
teachers in Prairies Elementary in the San Fernando Valley have emergency credentials, you would
expect the average reading scores of the 4th grade students in Prairie Elementary to be? - Answers 340
10% 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 be used to calculate the probability
that 3 pieces of mail have sufficient postage? - Answers None of the above
If the population is normal, the population standard deviation is known, and the sample size is 10, which
table would you use for calculating probability of the sample mean? - Answers Normal
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? - Answers You cannot reject the null
hypothesis
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? - Answers Smaller than the population standard
deviation
, 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? - Answers
The sample
A researcher 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 they were in favor of. The population is? - Answers All the voters
in Los Angeles
A market researcher has interviewed 80 heads of households and recorded whether the person was
never married, divorced, widowed, or married. The data is? - Answers Qualitative
A car dealer is studying his customers and the cars they buy. It is appropriate for him to use a mean to
describe? - Answers The mileage in miles per gallon of the car bought by a typical customer
Given that a sample of 25 had E x=75, and E(x-x) squared = 48, the mean and standard deviation are? -
Answers x=3.0 and s=square root of 48/24
A sample of dental offices found the number of cavities filled in the last week to be as follows: 12, 4, 4,
12, 12, 10. The median number of cavities filled is? - Answers 11
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 a sample
standard deviation of 2. Which of the following is correct? - Answers You cannot reject the null
hypothesis
Which of the following is ALWAYS true for test of hypothesis? - Answers None of the above
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 z 0.025 = 1.96 and t 0.025 = 1984 for
99 degrees of freedom. - Answers 0.12+-(1.96) square root of (0.12)(0.88)/100
If you have data on product output and total cost of production, you can estimate fixed and variable cost
by using? - Answers Linear regression
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? - Answers 16.6 cents
An investor has purchased stock in a firm. The investor believes that, and the end of the year, there is
0.10 probabilities that the stock will show a $6,000 profit, a 0.30 probability that the stock will show a
$4,000 profit and a 0.60 probability that the stock will show a $2,000 loss. The expected profit is $600. If
the best profit increases by $1,000 from $6,000 to $7,000, the expected profit? - Answers Will increase
by $100
