Tut sol week13

Tut sol week13 - BES Tutorial Sample Solutions, S1/10 WEEK...

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1 BES Tutorial Sample Solutions, S1/10 WEEK 13 TUTORIAL EXERCISES (To be discussed in the week starting May 31) 1. It is claimed by a manufacturer that its new type of light bulb is subject to less variability of bulb life. It is known that the former bulb type had a standard deviation of life of 150 hours. To test this claim, a consumer organization takes a sample of 41 of these new bulbs and measures their lives, finding a standard deviation of bulb life of 140 hours. Assuming light bulb lives are approximately normally distributed, test the manufacturer’s claim at a 5% level of significance. n = 41, s = 140 ܪ ൌ 150 ; ܪ ൏ 150 Under ܪ ሺ݊െ1ሻݏ ߪ 40 ൈ ݏ 150 ସଵିଵ Decision rule: Reject ܪ if ݈ܿܽܿݑ݈ܽݐ݁݀ ߯ ൏߯ ଴.ଽହ,ସ଴ ൌ 26.5093 Since calculated ߯ 40 ൈ 140 150 ൌ 34.84 ൐ ߯ ଴.ଽହ,ସ଴ ൌ 26.5093 we do not reject ܪ and conclude that the manufacturer’s claim of lower bulb life variability is not supported by the data.
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Tut sol week13 - BES Tutorial Sample Solutions, S1/10 WEEK...

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