A point estimate is a single value used to estimate a population parameter.
true
To determine the value of the standard error of the mean, the standard deviation is
divided by the sample size.
false
When using the t distribution to calculate a confidence interval, we assume that the
the population of interest is normal or nearly normal.
true
The mean number of travel days per year for salespeople employed by three hardware
distributors needs to be estimated with a 0.90 degree of confidence. For a small pilot
study, the mean was 150 days and the standard deviation was 14 days. If the populatio
133
The mean weight of trucks traveling on a particular section of I-475 is not known. A
state highway inspector needs an estimate of the population mean. He selects and weighs
a random sample of 49 trucks and finds the mean weight is 15.8 tons. The populatio
14.7 and 16.9
Which of the following is a point estimate for the population mean (�)?
x^-
What is the interpretation of a 96% confidence level?
Approximately 96 out of 100 such intervals would include the true value of the
population parameter.
Which statement(s) is/are correct about the t distribution?
A) Its dispersion is based on degrees of freedom. B) The mean is zero.
C) Its shape is symmetric.
(*D) All apply.)
What kind of distribution is the t distribution?
Continuous
Which of the following is NOT necessary to determine how large a sample to select from
a population?
A) The maximum allowable error in estimating the population parameter
(*B)The size of the population)
C) The level of confidence in estimating the population parameter
D) An estimate of the population variation
A confidence interval for a population mean ________.
estimates a likely interval for a population mean
A university surveyed recent graduates of the English Department for their starting
salaries. Four hundred graduates returned the survey. The average salary was $25,000,
with a standard deviation of $2,500. What is the best point estimate of the populatio
$25,000
A university surveyed recent graduates of the English Department for their starting
salaries. Four hundred graduates returned the survey. The average salary was $25,000.
The population standard deviation was $2,500. What is the 95% confidence interval for
[$24,755, $25,245]
A group of statistics students decided to conduct a survey at their university to find the
average (mean) amount of time students spent studying per week. Assuming a
population standard deviation of six hours, what is the required sample size if the error
554
A group of statistics students decided to conduct a survey at their university to estimate
the average (mean) amount of time students spent studying per week. They sampled 554
students and found a mean of 22.3 hours per week. Assuming a population standar
[21.64, 22.96]
A survey of 50 retail stores revealed that the average price of a microwave was $375,
with a sample standard deviation of $20. If 90% and 95% confidence intervals were
developed to estimate the true cost of the microwave, what similarities would they have
A) Both use the same t statistic
*B) Both use the same point estimate of the population mean
C) Both use the same z statistic
D) Both have the same confidence level
A survey of 25 grocery stores revealed that the mean price of a gallon of milk was $2.98,
with a standard error of $0.10. What is the 95% confidence interval to estimate the true
$2.77 to $3.19
A survey of an urban university (population of 25,450) showed that 750 of 1,100
students sampled attended a home football game during the season. Using the 99% level
of confidence, what is the confidence interval for the proportion of students attending a
[0.6464, 0.7172]
A survey of households in a small town showed that in 850 of 1,200 sampled
households, at least one member attended a town meeting during the year. Using the 99%
level of confidence, what is the confidence interval for the proportion of households
represe
[0.674, 0.742]
A survey of households in a small town showed that in 850 of 1,200 sampled
households, at least one member attended a town meeting during the year. Using the 99%
level of confidence, what is the confidence interval for the proportion of households
represe
0.87
A survey of households in a small town showed that in 500 of 1,200 sampled
households, at least one member attended a town meeting during the year. Using the 95%
level of confidence, what is the confidence interval for the proportion of households
represe
[0.389, 0.445]
A sample of 50 is selected from a known population of 250 elements. The population
standard deviation is 15. Using the finite correction factor, what is the standard error of
the sample means?
1.90
A sample of 500 students is selected from a known population of 15000 students to
construct a 99% confidence interval for the average SAT score. What correction factor
should be used to compute the standard error?
0.9832
If 95% and 98% confidence intervals were developed to estimate the true cost of an MP3
player with a known population standard deviation, what differences would they have?
A) The standard errors would be different.
B) The sample sizes would be different.
C) The point estimates of the population mean would be different.
*D) The z statistics would be different
Knowing the population standard deviation, a 95% confidence interval infers that the
population mean ________.
A) is too large
B) is between 0 and 100%
C) is within �1.96 standard deviations of the sample mean
*D) is within �1.96 standard errors of the sample mean