Question

In a random sample of 64 light bulbs, the mean lifetime was 1217 hours with sample standard deviation of 52 hours. a. Calculate a two-sided 96% confidence interval for the mean lifetime of this type of light bulb. b. If the true population mean lifetime is 1210, what is the approximate probability that the average lifetime of 64 randomly selected light bulbs is greater than 1217?

Answer 1

\( \large CI = \bar{x} \pm z \frac{s}{\sqrt{n}} \)

\(\bar{x}\) is your mean which is 1217

z is the z-value
and for a 96% confidence interval, the value would be 2.05
http://www.ltcconline.net/greenl/courses/201/Estimation/smallConfLevelTable.htm

and 's' is the standard deviation of 52

n is how many samples you have which is 64

Answer 2

can you calculate the confidence interval now?

Answer 3

yes thanks

Answer 4

Is this question answered?

Answer 5

yes

Answer 6

@trentw882 ?

Answer 7

Oh ok.

Answer 8

but thank u any way

Answer 9

Yeah Np.