The newest model of a car battery from a popular brand is supposed to have a lifetime of 60 months, but the lifetime varies slightly from battery to battery. It is known that the population of all lifetimes (in months) of this model of car battery is approximately normally distributed. You are a product reviewer who wants to estimate the standard deviation for this population with a random sample of 22 car batteries. Follow the steps below to construct a 99% confidence interval for the population standard deviation of all lifetimes of this model of car battery. (If necessary, consult a list of formulas.) (a)Click on "Take Sample" to see the results from the random sample. Take Sample Number of carbatteries Sample mean Sample standard deviation Sample variance 22 57.16 0.38 0.1444 To find the confidence interval for the population standard deviation, first find the confidence interval for the population variance. Enter the values of the point estimate of the population variance, the sample size, the left critical value, and the right critical value you need for your 99% confidence interval for the population variance. (Choose the correct critical values from the table of critical values provided.) When you are done, select "Compute". Critical values Confidence level Left critical value Right critical value 99% =χ20.9958.034 =χ20.00541.401 95% =χ20.97510.283 =χ20.02535.479 90% =χ20.9511.591 =χ20.0532.671 Point estimate of the population variance: Sample size: Left critical value: Right critical value: Compute 99% confidence interval for the population variance: 99% confidence interval for the population standard deviation: (b)Based on your sample, enter the values for the lower and upper limits to graph the 99% confidence interval for the population standard deviation of all lifetimes of this model of car battery. Round the values to two decimal places. 99% confidence interval for the population standard deviation: 0.001.00
The newest model of a car battery from a popular brand is supposed to have a lifetime of 60 months, but the lifetime varies slightly from battery to battery. It is known that the population of all lifetimes (in months) of this model of car battery is approximately normally distributed. You are a product reviewer who wants to estimate the standard deviation for this population with a random sample of 22 car batteries. Follow the steps below to construct a 99% confidence interval for the population standard deviation of all lifetimes of this model of car battery. (If necessary, consult a list of formulas.) (a)Click on "Take Sample" to see the results from the random sample. Take Sample Number of carbatteries Sample mean Sample standard deviation Sample variance 22 57.16 0.38 0.1444 To find the confidence interval for the population standard deviation, first find the confidence interval for the population variance. Enter the values of the point estimate of the population variance, the sample size, the left critical value, and the right critical value you need for your 99% confidence interval for the population variance. (Choose the correct critical values from the table of critical values provided.) When you are done, select "Compute". Critical values Confidence level Left critical value Right critical value 99% =χ20.9958.034 =χ20.00541.401 95% =χ20.97510.283 =χ20.02535.479 90% =χ20.9511.591 =χ20.0532.671 Point estimate of the population variance: Sample size: Left critical value: Right critical value: Compute 99% confidence interval for the population variance: 99% confidence interval for the population standard deviation: (b)Based on your sample, enter the values for the lower and upper limits to graph the 99% confidence interval for the population standard deviation of all lifetimes of this model of car battery. Round the values to two decimal places. 99% confidence interval for the population standard deviation: 0.001.00
The newest model of a car battery from a popular brand is supposed to have a lifetime of 60 months, but the lifetime varies slightly from battery to battery. It is known that the population of all lifetimes (in months) of this model of car battery is approximately normally distributed. You are a product reviewer who wants to estimate the standard deviation for this population with a random sample of 22 car batteries. Follow the steps below to construct a 99% confidence interval for the population standard deviation of all lifetimes of this model of car battery. (If necessary, consult a list of formulas.) (a)Click on "Take Sample" to see the results from the random sample. Take Sample Number of carbatteries Sample mean Sample standard deviation Sample variance 22 57.16 0.38 0.1444 To find the confidence interval for the population standard deviation, first find the confidence interval for the population variance. Enter the values of the point estimate of the population variance, the sample size, the left critical value, and the right critical value you need for your 99% confidence interval for the population variance. (Choose the correct critical values from the table of critical values provided.) When you are done, select "Compute". Critical values Confidence level Left critical value Right critical value 99% =χ20.9958.034 =χ20.00541.401 95% =χ20.97510.283 =χ20.02535.479 90% =χ20.9511.591 =χ20.0532.671 Point estimate of the population variance: Sample size: Left critical value: Right critical value: Compute 99% confidence interval for the population variance: 99% confidence interval for the population standard deviation: (b)Based on your sample, enter the values for the lower and upper limits to graph the 99% confidence interval for the population standard deviation of all lifetimes of this model of car battery. Round the values to two decimal places. 99% confidence interval for the population standard deviation: 0.001.00
The newest model of a car battery from a popular brand is supposed to have a lifetime of
60
months, but the lifetime varies slightly from battery to battery. It is known that the population of all lifetimes (in months) of this model of car battery is approximately normally distributed. You are a product reviewer who wants to estimate the standard deviation for this population with a random sample of
22
car batteries.
Follow the steps below to construct a
99%
confidence interval for the population standard deviation of all lifetimes of this model of car battery. (If necessary, consult a list of formulas.)
(a)Click on "Take Sample" to see the results from the random sample.
Take Sample
Number of car batteries
Sample mean
Sample standard deviation
Sample variance
22
57.16
0.38
0.1444
To find the confidence interval for the population standard deviation, first find the confidence interval for the population variance.
Enter the values of the point estimate of the population variance, the sample size, the left critical value, and the right critical value you need for your
99%
confidence interval for the population variance. (Choose the correct critical values from the table of critical values provided.) When you are done, select "Compute".
Critical values
Confidence level
Left critical value
Right critical value
99%
=χ20.9958.034
=χ20.00541.401
95%
=χ20.97510.283
=χ20.02535.479
90%
=χ20.9511.591
=χ20.0532.671
Point estimate of the population variance:
Sample size:
Left critical value:
Right critical value:
Compute
99%
confidence interval for the population variance:
99%
confidence interval for the population standard deviation:
(b)Based on your sample, enter the values for the lower and upper limits to graph the
99%
confidence interval for the population standard deviation of all lifetimes of this model of car battery. Round the values to two decimal places.
99% confidence interval for the population standard deviation:
0.001.00
Features Features Normal distribution is characterized by two parameters, mean (µ) and standard deviation (σ). When graphed, the mean represents the center of the bell curve and the graph is perfectly symmetric about the center. The mean, median, and mode are all equal for a normal distribution. The standard deviation measures the data's spread from the center. The higher the standard deviation, the more the data is spread out and the flatter the bell curve looks. Variance is another commonly used measure of the spread of the distribution and is equal to the square of the standard deviation.
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