SAMPLING AND SAMPLING DISTRIBUTIONS
1. Since the sample size [n] is alway smaller than the size of the
population[n], then the sample mean[x]
a. must alway be smaller than the population mean[u]
b. must be larger than the population mean[u]
c. must be equal to the population mean[u]
d. must be zero
2. Whenever the population has a normal probability distribution, the
sampling distribution of the sample
mean[x] has a normal probablitiy distribution
a. for only large sample sizes
b. for only small sample sizes
c. for any sample size
d. for only sample sizes >= 30
e. none of the above answers is correct
3. A simple random sample from an infinite population is a sample
selected such that
a. each element selected come from the same population
b. each element is selected independently
c. both a and b must be satisified
d. the probablilty of being selected changes
e. none of the above answers is correct
4. If we consider the simple random sampling process as an
experiment, the sample mean[x] is
a. always zero
b. always smaller than the population mean[u]
c. a random variable
d. exactly equal to the population mean[u]
e. none of the above answers is correct
INTERVAL TESTING
5. The confidence associated with an interval estimate is called
a. significance
b. degree of association
c. confidence level
d. precision
e. none of the above answers is correct
6. From a population which is normally distributed, a sample of [n=25
elements] is selected and the
standard deviation [s] of the sample is computed. For the interval
estimation of the population mean[u], the
proper distribution to use is the
a. normal distribution
b. t distribution
c. t distribution with 25 degrees of freedom
d. t distribution with 24 degrees of freedom
e. none of the above answers is correct
7. A 95% confidence interval for a population mean[u] show the values
25.1 to 28.3. What is the appropriate
conclusion?
a. 95% of all sample means[x] should be between 25.1 to 28.3
b. 95% of the time, the population mean[u] will be within this
interval; 5% of the time it will be
outside of this interval
c. Since 95% of all confidence intervals contain the population
mean[u], we are 95% confident this
interval includes it
d. all of the above answers is correct
e. none of the above answers is correct
8. In determining the sample size[n] necessary to estimate a
population proportion[p], which of the following
information in not needed
a. the maximum size of the sampling error that con be tolerated
b. the confidence level required
c. a preliminary estimate of the true population proportion[p]
d. the mean of the population [u]
e. none of the above answers is correct
HYPOTHESIS TESTING
9. In hypothesis testing, if valid sample data indicate the null
hypothesis is to be rejected
a. no conclusion can be drawn from the test
b. the alternative hypothesis may also be rejected
c. the data must have been accumulated incorrectly
d. the sample size[n] was too small
e. none of the above answers is correct
10. The level of significance in hypothesis testing is the probability
of
a. not rejecting a true null hypothesis
b. not rejecting a false null hypothesis
c. rejecting a true null hypothesis
d. could be any of the above, depending upon the situation
e. none of the above answers is correct
11. If a hypothesis test leads to the rejection of the null
hypothesis
a. a Type I error is always committed
b. a Type II error is always committed
c. a Type I error may have been committed
d. a Type II error may have been committed
e. None of the above answers is correct
12. For a two-tailed test and a sample size of [n=40], the null
hypothesis will not be rejected at the 5% level
if the standardized test statistic is
a. between -1.96 and 1.96
b. greater than 1.96
c. less than 1.645
d. greater than -1.645
e. none of the above answers is correct
SAMPLING AND SAMPLING DISTRIBUTIONS
13. The mean wage rate for hourly workers at General Motors is
[u=$14.25] per hour. Assume that the population
standard deviation[o=$2.00]. What is the probablility that the sample
mean [x] is at least $13.80 per hour,
given a random sample of [n=50 workers]?
a. .0559
b. .4441
c. .5559
d. .9441
e. none of the above answers is correct
14. The average weekly earnings of the plumbers in a city is [u=$750]
with a standard deviation of[o=$40].
Assume that we select a random sample of [n=64 plumbers], what is the
probablility that the sample mean [x] will
be greater than $740?
a. .0228
b. .0987
c. .4772
d. .5987
e. none of the above answers is correct
INTERVAL ESTIMATION
15. The owner of a major Atlanta restaurant wanted to estimate the
mean amount spent per customer for dinner
meals. A random sample of [n=49 customers] over a 3-week period
revealed a sample average of [x=$12.60] spent,
with a population standard devation [o=$2.50]. Determine a 95%
confidence interval(rounded to the nearest cent)
for the average amount spent per dinner meal of all his customers
a. $12.01 to $13.19
b. $11.76 to $13.44
c. $11.90 to $13.30
d. unable to detemine because of insufficient data
e. none of the above answers is correct
16. A random sample of [n=64 children] of working mothers showed that
they were absent from school an sample
average of [x=5.3 days] per term, with a standard deviations [s=1.8
days]. Provide a 96% confidence interval
for the average number of days absent per term for all the students.
a. 5.2321 days to 5.3762 days
b. 4.8151 days to 5.7543 days
c. 4.8387 days to 5.7613 days
d. 4.7722 days to 5.8392 days
e. none of the above answers is correct
HYPOTHESIS TESTING
17. Tuff wear Tire Company in findlay ohio, wants its advertising
company to put together an ad campaign that
will claim its low-end cost line tires will last at least {u=28,000
miles]. Tests with a random sample [n=30
tires] show a sample mean {x=27,500 miles] with a sample standard
devation [s=1000 miles]. At a .05 level of
significance, these tests indicate
a. reject h_o: z of -2.7386 < -1.6450
b. reject h_o: z of -2.7386 < 1.6450
c. do not reject h_o: z of 1.6450 < 2.7386
d. do not reject h_o: z of -1.6450 < 2.7368
e. none of the above answers is correct
18. Form a population of cereal boxes marked "12 ounces", a random
sample of [n=16 boxes] is selected and the
contents of each box is weighed. The sample revealed a sample mean
[x=11.7 ounces], with a standard deviation
[s=0.8 ounces]. Test to see if the population mean [u] is at least 12
ounces. Use a 0.05 level of
significance.
a. reject h_o: t of 1.753 > -1.500
b. reject h_o: t of -1.500 < -1.753
c. Do not reject h_o: t of -1.645 > -1.753
d. Do not reject h_o: t of -1.500 < 1.753
e. none of the above answers is correct
SAMPLING
19. In a town of Sprindale, 30% of the families [p=.30] reqularly
plant vegtable gardens. A random sample of
[n=100 families] is selected for a particular study. What is the
probability that the sample proportion[p] ,
the proportion of families who plant a vegetable garden, is between
(.20) and (.40)?
a. .0146
b. .0292
c. .4854
d. .9708
e. non of the above answers is correct
INTERVAL ESTIMATION
20. The proprietor of a boutique in New York wanted to determine the
average age of his customers. A random
sample of [n=25 customers] revealed an average age of [x=32 years],
with a standard deviation of [s=8 years].
Determine a 95% confidence interval estimate for the average age of
all his customers.
a. 28.6976 to 35.3024
b. 28.8640 to 35.1360
c. 29.2624 to 34.7376
d. 29.3680 to 34.6320
e. none of the above answers is correct
HYPOTHEISIS TESTING
21. The US Bureau of the Census reported mean hourly earnings in the
wholesale trade industry of [u=$9.70 per
hour] in 1987. A random sample of [n=49] wholesale workers in a
particular city showed a sample mean hourly
wage of [x=$9.30 per hour] with a standard deviation of [s=1.06 per
hour]. Use a H_o:u=$9.70 and H_a: not =
$9.70. Test to see if wage rates in the city differ significantly from
the reported $9.70. Use alpha =0.05
a. reject h_o: z of 2.6667 > 1.960
b. reject h_o: z of 2.6667 > 1.645
c. reject h_o: z of -2.667 < -1.960
d. do not reject h_o: z of 0.3810 < 1.960
e. none of the above answers is correct |
