WorksheetsConfidence Intervals
Total questions: 13
Worksheet time: 34mins
A sample size of n = 64 is drawn from a population whose standard deviation is σ = 5.6.
Find the margin of error for a 99% confidence interval for µ.
1.799
1.798
1.803
A large sample has mean of 7.1 and Standard Error of 2.3.
Construct a 90% Confidence Interval for the population mean µ (to two decimal places).
(3.32, 10.88)
(3.8, 7.1)
(3.3, 10.9)
(3.3165, 10.8835)
An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.
What is the point estimate?
75
105.2
10
0.90
An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.
Find the critical value.
0.90
1.155
1.645
±1.645
An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.
Find the Standard Error.
75
10
105.2
1.155
An IQ test was given to a simple random sample of 75 students at a certain college. The sample mean score was 105.2. Scores on this test are known to have a standard deviation of 10. It is desired to construct a 90% confidence interval for the mean IQ scores of the students at the college.
Find the Margin of Error to two decimal places.
1.90
1.89
1.899
1.99
The lifetime of a certain type of batter is known to be normally distributed with a standard deviation of 20 hours. A sample of 50 batteries had a mean lifetime of 120.1 hours. It is desired to construct a 99% confidence interval for the mean lifetime of this type of battery.
What is the Confidence Interval to one decimal place?
(114.5, 125.6)
(112.8, 127.4)
(112.82, 127.38)
(114.56, 125.64)
If the 95% Confidence Interval for a population mean is (114.56, 125.54), then is it likely that the true population mean µ is greater than 130?
Yes
No
Not enough information
I have no idea what you're asking of me
A population has a standard deviation of σ = 17.3. How large of a sample must be drawn so that a 95% confidence interval for µ will have a Margin of Error equal to 1.4?
586.6
587
586
585
A person selects a random sample of 15 credit cards and determines the annual interest rate, in percent, of each one. The sample mean is 12.42 with a sample standard deviation of 1.3. It is desired to construct a 90% Confidence Interval.
Find the Standard Error to three decimal places.
0.336
0.33566
13.156
0.087
You are given two sets of data measuring the same information, both with the same sample size. Set A has a larger Standard Error than Set B. If you were looking for a 99.8% Confidence Interval, which set would have a larger Margin of Error?
Set A
Set B
Not enough information
I have no idea what you're asking me to do
True or False:
The more confident you want to be, the smaller your confidence interval will be.
True
False
True or False:
The larger your confidence interval is, the more sure (higher confidence level) you can be.
True
False
