QMB Exam 2
A single value that best describes the population of interest - Answer-Point estimate
Sample mean is a ___ of the unknown population mean - Answer-Point estimate
The sample proportion is a ___ of the unknown population proportion - Answer-Point estimate
What is the problem with point estimates? - Answer-They do not provide any information about their
accuracy
Provides additional information about verifiability - Answer-Interval estimate
An interval estimate around a sample mean that provides us with a range within which the true
population is expected to lie - Answer-Confidence interval for the mean
The probability that the interval estimate will include the population parameter of interest - Answer-
Confidence level
When finding confidence intervals for the mean with stdev known, what are the (2) assumptions? -
Answer-1. Sample size is at least 30
2. Population standard deviation is known
, F: formula for the standard error of the mean? - Answer-Population standard deviation/ square root of
sample size
The __ describe the range in which we have some degree of confidence that the actual population lies -
Answer-Limits
F: formula for upper confidence limit for the mean when population standard deviation is known -
Answer-Sample mean + (critical z score)(standard error of mean)
F: formula for lower confidence limit for the mean when population standard deviation is known -
Answer-Sample mean - (critical z score)(standard error of mean)
P: The airline wants to estimate the number of tickets sold for a daily flight between Dallas and Denver.
Suppose a sample of 35 flights flights gives a sample mean of 145.5 (Assume stdev is 30.2) - Answer-
Based on our sample mean of 145.5 we are 90% confident that the population mean number of tickets
sold is between 137.10 and 153.90
The amount added to and subtracted to form the confidence interval - Answer-Margin of error
If the sample size is increased and the confidence level is constant, what will happen to the margin of
error - Answer-It will decrease, making the confidence interval more precise
T or F: A confidence interval means that there is x% probability that the interval contains the true
population mean - Answer-False
T or F: A confidence interval means that although the population mean may or may not be in this
interval, close to x% of a large number of sample means drawn from this population will produce
confidence intervals that include that population's mean - Answer-True
A single value that best describes the population of interest - Answer-Point estimate
Sample mean is a ___ of the unknown population mean - Answer-Point estimate
The sample proportion is a ___ of the unknown population proportion - Answer-Point estimate
What is the problem with point estimates? - Answer-They do not provide any information about their
accuracy
Provides additional information about verifiability - Answer-Interval estimate
An interval estimate around a sample mean that provides us with a range within which the true
population is expected to lie - Answer-Confidence interval for the mean
The probability that the interval estimate will include the population parameter of interest - Answer-
Confidence level
When finding confidence intervals for the mean with stdev known, what are the (2) assumptions? -
Answer-1. Sample size is at least 30
2. Population standard deviation is known
, F: formula for the standard error of the mean? - Answer-Population standard deviation/ square root of
sample size
The __ describe the range in which we have some degree of confidence that the actual population lies -
Answer-Limits
F: formula for upper confidence limit for the mean when population standard deviation is known -
Answer-Sample mean + (critical z score)(standard error of mean)
F: formula for lower confidence limit for the mean when population standard deviation is known -
Answer-Sample mean - (critical z score)(standard error of mean)
P: The airline wants to estimate the number of tickets sold for a daily flight between Dallas and Denver.
Suppose a sample of 35 flights flights gives a sample mean of 145.5 (Assume stdev is 30.2) - Answer-
Based on our sample mean of 145.5 we are 90% confident that the population mean number of tickets
sold is between 137.10 and 153.90
The amount added to and subtracted to form the confidence interval - Answer-Margin of error
If the sample size is increased and the confidence level is constant, what will happen to the margin of
error - Answer-It will decrease, making the confidence interval more precise
T or F: A confidence interval means that there is x% probability that the interval contains the true
population mean - Answer-False
T or F: A confidence interval means that although the population mean may or may not be in this
interval, close to x% of a large number of sample means drawn from this population will produce
confidence intervals that include that population's mean - Answer-True
