Question

In a random sample of 100 batteries produced by a certain method, the average lifetime was 140 hours, and the standard deviation was 20 hours. $ \bar{x} \pm 1.96 \frac{\sigma}{\sqrt{n}} $ a. Find a 90% confidence interval for the population mean life of batteries produced by this method. b. Find a 95% confidence interval for the population mean life of batteries produced by this method. c. An engineer claims that the mean lifetime is between 137 and 143 hours. With what level of confidence can this statement be made?

          In a random sample of 100 batteries produced by a certain method, the average lifetime was 140 hours, and the standard deviation was 20 hours.
$ \bar{x} \pm 1.96 \frac{\sigma}{\sqrt{n}} $
a. Find a 90% confidence interval for the population mean life of batteries produced by this method.
b. Find a 95% confidence interval for the population mean life of batteries produced by this method.
c. An engineer claims that the mean lifetime is between 137 and 143 hours. With what level of confidence can this statement be made?

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In a random sample of 100 batteries produced by a certain method, the average lifetime was 140 hours, and the standard deviation was 20 hours.
x̅± 1.96 (σ)/(√(n))
a. Find a 90% confidence interval for the population mean life of batteries produced by this method.
b. Find a 95% confidence interval for the population mean life of batteries produced by this method.
c. An engineer claims that the mean lifetime is between 137 and 143 hours. With what level of confidence can this statement be made?

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Elementary Statistics a Step by Step Approach

Allan G. Bluman 9th Edition

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Solved by Expert Rakesh Singhi

05/30/2022

Step 1

Step 1: To find the confidence interval for the population mean life of batteries produced by this method, we can use the formula: \[ \bar{x} \pm z \left( \frac{s}{\sqrt{n}} \right) \] where: - \(\bar{x}\) = sample mean (140 hours) - \(s\) = standard deviation (20 Show more…

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/26/22218ets In a random sample of 100 batteries produced by a certain method, the average lifetime was 140 hours, and the standard deviation was 20 hours. [2+1+1=4M] 865 by/11/2 a. Find a 90% confidence interval for the population mean life of batteries produced by this method. 1/26- b. Find a 95% confidence interval for the population mean life of batteries produced by this method. c. An engineer claims that the mean lifetime is between 137 and 143 hours. With what level of confidence can this statement be made? 702218et 11/26 an le of batteries produced by this method An engineer claims that the mean lifetime is between 137 and 143 hours. With what level of confidence can this statement be made?

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