The management of an electrical manufacturing plant determined that the mean life of their 10 watt...
The management of an electrical manufacturing plant determined that the mean life of their 10 watt bulbs is 10 , 000 hours with a standard deviation of 500 hours. The lives are normally distributed. a) What is the probability that a randomly selected bulb has a life of more than 10 , 950 hours? Give your answer rounded to 4 decimal places. b) Using the Empirical Rule, we expect about 68 % of the values in a normal distribution to lie within one standard deviation of the mean. Between what two values will 68 % of the bulbs' lives fall? ____ and _____
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The management of an electrical manufacturing plant determined
that the mean life of their 10 watt...
An electrical firm which manufactures a certain type of bulb wants to estimate its mean life....
An electrical firm which manufactures a certain type of bulb wants to estimate its mean life. The life of the light bulb is normally distributed with a standard deviation of 40 hours. A random sample of 36 bulbs resulted in a mean of 200 hours. a) (3 points) Construct a 92% confidence interval for the mean life of all light bulbs the firm manufactures. b) (4 points) How many bulbs should be tested so that we can be 92% confident...
An electrical firm which manufactures a certain type of bulb wants to estimate its mean life....
An electrical firm which manufactures a certain type of bulb wants to estimate its mean life. The life of the light bulb is normally distributed with a standard deviation of 40 hours. A random sample of 36 bulbs resulted in a mean of 200 hours. a) (3 points) Construct a 92% confidence interval for the mean life of all light bulbs the firm manufactures. b) (4 points) How many bulbs should be tested so that we can be 92% confident...
Construct the 95% confidence interval for mean life
a) The life hours of a 75-watt light bulb is known to be approximately normally distributed with standard deviation 25 hours. A random sample of 25 bulbs has a mean life of x 1050 hours.Construct the 95% confidence interval for mean life, .
The mean life of a particular brand of light bulb is 1200 hours and the standard...
The mean life of a particular brand of light bulb is 1200 hours and the standard deviation is 75 hours. Tests show that the life of the bulb is approximately normally distributed. What is the range of hours that approximately 68% of the bulbs will last?
An electrical firm manufactures light bulbs that have a length of life that is approximately norm...
An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed with a standard deviation of 20 hours. If a sample of 30 bulbs has an average life of 780 hours, how large a sample is needed if we wish to be 95% confident that our sample mean will be within 4 hours of the true mean. a. 62 b. 68 c. 100 d. 97
An electrical firm manufactures light bulbs that have a length of life that is approximately normally...
An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed with a standard deviation of 20 hours. If a sample of 30 bulbs has an average life of 780 hours, how large a sample is needed if we wish to be 95% confident that our sample mean will be within 4 hours of the true mean. a. 62 b. 68 c. 100 d. 97
The life in hours of a 75-watt light bulb is known to be normally distributed with...
The life in hours of a 75-watt light bulb is known to be normally distributed with = 23 hours. A random sample of 20 bulbs has a mean life of X= 1011 hours. Suppose that we wanted the margin of error in estimating the mean life from the two-sided confidence interval to be five hours at 95% confidence. What sample size should be used? Round up the answer to the nearest integer. Statistical Tables and Charts
The life in hours of a 75-watt light bulb is known to be normally distributed with...
The life in hours of a 75-watt light bulb is known to be normally distributed with σ = 27 hours. A random sample of 20 bulbs has a mean life of x Overscript bar EndScripts = 1015 hours. Suppose that we wanted the total width of the two-sided confidence interval on mean life to be six hours at 95% confidence. What sample size should be used? Round up the answer to the nearest integer.
An electrical firm manufactures light bulbs that have a length of life that is approximately normally...
An electrical firm manufactures light bulbs that have a length of life that is approximately normally distributed with a standard deviation of 40 hours. If a sample of 30 bulbs has an average life of 780 hours, find a 96% confidence interval for the population mean of all bulbs produced by this firm. How large a sample is needed if we wish to be 96% confident that our sample mean will be within 10 hours of the true mean?
= 25 hours. A random sample of 22 bulbs The life in hours of a 75-watt...
= 25 hours. A random sample of 22 bulbs The life in hours of a 75-watt light bulb is known to be normally distributed with has a mean life of K = 1014 hours. (a) Construct a 95% two-sided confidence interval on the mean life. Round your answers to the nearest integer (e.g. 9876). (b) Construct a 95% lower-confidence bound on the mean life. Compare the lower bound of this confidence interval with the one in part (a). Round your...
An electrical firm which manufactures a certain type of bulb wants to estimate its mean life. The life of the light bulb is normally distributed with a standard deviation of 40 hours. A random sample of 36 bulbs resulted in a mean of 200 hours. a) (3 points) Construct a 92% confidence interval for the mean life of all light bulbs the firm manufactures. b) (4 points) How many bulbs should be tested so that we can be 92% confident...
The life in hours of a 75-watt light bulb is known to be normally distributed with = 23 hours. A random sample of 20 bulbs has a mean life of X= 1011 hours. Suppose that we wanted the margin of error in estimating the mean life from the two-sided confidence interval to be five hours at 95% confidence. What sample size should be used? Round up the answer to the nearest integer. Statistical Tables and Charts
= 25 hours. A random sample of 22 bulbs The life in hours of a 75-watt light bulb is known to be normally distributed with has a mean life of K = 1014 hours. (a) Construct a 95% two-sided confidence interval on the mean life. Round your answers to the nearest integer (e.g. 9876). (b) Construct a 95% lower-confidence bound on the mean life. Compare the lower bound of this confidence interval with the one in part (a). Round your...
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