Question

Problem 2 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 96% confidence interval for the population mean of all bulbs produced by this firm. Infer, as to how large a sample is needed if we wish to be 96% confident that our sample mean will be within 10hours of the true mean?

Name: problem 2 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 89661
Uploaded: 2023-07-19T22:39:25-08:00
Duration: 2 min 38 s
Channel: Lien Le
Description: problem 2 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 89661

          Problem 2
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 96% confidence interval for the
population mean of all bulbs
produced by this firm. Infer, as to how large a sample is needed
if we wish to be 96% confident
that our sample mean will be within 10hours of the true
mean?

Added by Roger M.

Elementary Statistics a Step by Step Approach

Allan G. Bluman 9th Edition

Instant Answer

Solved by Expert Lien Le

07/19/2023

Step 1

Given: Population standard deviation, σ = 40 Sample size, n = 30 Sample mean, x̄ = 780 Confidence level, 96% Critical value for a 96% confidence level from the standard normal distribution table is 2.0537. Calculate the margin of error: Margin of error (ME) = Show more…

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Problem 2 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 96% confidence interval for the population mean of all bulbs produced by this firm. Infer, as to how large a sample is needed if we wish to be 96% confident that our sample mean will be within 10hours of the true mean?