Question

9. The standard deviation of the lifetime of a certain type of lightbulb is known to...

9. The standard deviation of the lifetime of a certain type of lightbulb is known to equal 100 hours. A sample of 169 such bulbs had an average life of 1350 hours. Find a
(a) 90percent (b) 95percent (c) 99percent
confidence interval estimate of the mean life of this type of bulb.
Math   Statistics-And-Probability   
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Homework Answers

Answer #1

Confidence Interval :-



Lower Limit =
Lower Limit = 1337.3473
Upper Limit =
Upper Limit = 1362.6527
90% Confidence interval is ( 1337.3473 , 1362.6527 )

Confidence Interval :-



Lower Limit =
Lower Limit = 1334.9234
Upper Limit =
Upper Limit = 1365.0766
95% Confidence interval is ( 1334.9234 , 1365.0766 )

Confidence Interval :-



Lower Limit =
Lower Limit = 1330.1859
Upper Limit =
Upper Limit = 1369.8141
99% Confidence interval is ( 1330.1859 , 1369.8141 )

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