WorksheetsMargin of Error and Confidence Interval (95%)
Total questions: 19
Worksheet time: 38mins
For a class project, a student in a statistics class surveys the monthly rent for 32 unfurnished one-bedroom apartments in Boston and finds the mean monthly rent to be $1400 with a standard deviation of $220.
Find the margin of error for the sample mean. (assuming 95% confidence) Round to the nearest hundredth
$77.78
$4.31
$188.78
$494.97
For a class project, a student in a statistics class surveys the monthly rent for 32 unfurnished one-bedroom apartments in Boston and finds the mean monthly rent to be $1400 with a standard deviation of $220.
Find the 95% confidence interval for the population mean Round to the nearest hundredth
[1322.22, 1477.78]
[1395.69, 1404.31]
[1211.22, 1588.78]
[905.03, 1894.97]
A random sample of 45 life insurance policy holders showed that the average premiums paid on their life insurance policies was $340 per year with a standard deviation of $62. Construct a 95% confidence interval for the population mean. Round to the nearest hundredth
[321.52, 358.48]
[238.63, 441.37]
[253.64, 426.36]
[328.57, 351.43]
A survey was conducted where 150 high school students were asked the average amount of time they spent doing household chores in one week. The data collected resulted in a mean time of 180.5 minutes with a standard deviation of 5.5 minutes. Which of these represents a 95% confidence interval for the mean weekly hours spent doing household chores of all high school students?
[171.5, 189.5]
[175, 186]
[178.3, 182.8]
[179.6, 181.4]
A sample of 121 high school seniors were surveyed on their level of school spirit on a scale of 0-100. The sample mean of this survey is 86. The known population standard deviation is 14 for all seniors in the class. Which of these is a 95% confidence interval for the population mean?
[82.7, 89.3]
[83.5, 88.5]
[83.9, 88.1]
[85.9, 86.1]
Researchers want to estimate with 95% confidence the true mean pulse rate of American adult males who jog at least 15 miles per week. They survey 21 males and find the sample mean pulse rate to be 52.6 beats per minute and a standard deviation of 3.22 beats per minute. Find the margin of error for the mean pulse rate of all American adult males who jog at least 15 miles per week. Round to the nearest tenth.
1.4 beats per minute
1.7 beats per minute
0.9 beats per minute
4.1 beats per minute
The operations manager of a large production plant wants to estimate the mean amount of time a worker takes to assemble a new electric component. Assume the standard deviation of the assembly time is 3.6 minutes. After observing 120 workers, the manager found their mean assembly time to be 16.2 minutes. Construct a 95% confidence interval for the estimate of the mean assembly time. Round to the nearest hundredth.
[15.54, 16.86]
[13.24, 19.16]
[14.41, 17.99]
[10.94, 21.46]
Complete the following statement about the change in size.
If you increase the size of your sample, the ME will . . . .
increase
decrease
stay the same
A sample of 20 cupcakes found the interval for average calories to be (150, 350). Which is the correct interpretation of the 95% confidence interval?
We are 95% confident that the true mean caloric content can be found with a sample of 150 to 350 cupcakes.
We are 95% confident that the interval (150, 350) captures the true average caloric content.
We are 95% confident that a sample of 20 cupcakes will find 250 calories per cupcake.
None of these are correct.
Previous studies show that the standard deviation for work time is 3 hours, and a survey of 40 students has a mean of 9.8 work hours per week.
The 95% confidence interval is…
(8.84, 10.76)
(8.87, 10.73)
(9.02, 10.58)
(9.00, 10.60)
The average waist size for teenage males is 29 inches with a standard deviation of 1.4 inch.
If waist sizes are normally distributed, estimate the proportion of teenagers who will have waist sizes greater than 31.8 inches?
99.7%
13.5%
16%
2.5%
Given a mean of 75 and a standard deviation of 7, what percentage of scores are between 54 and 96?
34%
99.7%
95%
2.5%
True or False: The more confident you want to be, the smaller your confidence interval will be.
True
False
Suppose that a confidence interval for hours worked by students was computed to be (8.82, 10.78). Which of these is a valid interpretation of this confidence interval?
There is a 95% probability that the average number of hours worked by all students is between 8.82 and 10.78 hours.
There is a 95% probability that a randomly selected student worked between 8.82 and 10.78 hours.
We are 95% confident that the population average number of hours worked by all students is between 8.82 and 10.78 hours.
We are 95% confident that the average number of hours worked by the students in our sample is between 8.82 and 10.78 hours.
