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 720 hours, find a 96% confidence interval for the population mean of all bulbs produced by this firm.

Calculus For The Life Sciences
2nd Edition
ISBN:9780321964038
Author:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Publisher:GREENWELL, Raymond N., RITCHEY, Nathan P., Lial, Margaret L.
Chapter13: Probability And Calculus
Section13.2: Expected Value And Variance Of Continuous Random Variables
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5. Please answer the following probability question.
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 720 hours, find a 96% confidence interval for the
population mean of all bulbs produced by this firm.
Transcribed Image Text: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 720 hours, find a 96% confidence interval for the population mean of all bulbs produced by this firm.
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