Confidence intervals

[emiizladii]

The new Twinkle bulb has a mean life of hours with a standard deviation hours. A random sample of 50 light bulbs is selected from inventory. The sample mean was found to be 500 hours.

a. Find the margin of error E for a 95% confidence interval.


b. Construct a 95% confidence interval for the mean life, ? of all Twinkle bulbs.

 

[galactus]

The new Twinkle bulb has a mean life of hours with a standard deviation hours. A random sample of 50 light bulbs is selected from inventory. The sample mean was found to be 500 hours.

a. Find the margin of error E for a 95% confidence interval.

Use the formula I showed you in the minimum sample size post for E.

b. Construct a 95% confidence interval for the mean life, ? of all Twinkle bulbs.

The value you found in part a, add it to and subtract it from the mean.