Question

The quality control manager at a light bulb factory needs to determine whether the mean life of a large shipment of light bulbs is equal to 375.00 hours. The STDEV.P = 100.00 hours. A random sample of 64 light bulbs indicates a MEAN.S of 350.00 hours a) At the 0.05 level of significance, is there evidence that the mean life is different from 375.00 hours? (define the Ho and H1) (explain whether you will reject or not reject HO) (check figure: Z-Stat = -2.00) b) Construct a 95.00% confidence interval estimate of the population mean life of the light bulbs (this will be the lower and upper range) (check figure: lower range = 325.50)

Answer 1

Answer:-

Page one

Totest Hoi el=375 vis HiM # 375 test statistic, - 2= x= 1 ntno o - slun whele ž= 350, s=100; n=64, O20:05 put this value in egr 0 we get 2350-375 = -2.00 100/Sri to= loftical value. tn.1,a/2=463,0.05% t62.0.025 = 1.998 decision: 1 treitical value is we fReject Hof conclusions there is not sufficient evidence to suggest that the mean life of a large shipment of Tight is equal to 345000 hours at significance level o.os. - - Scanned with CamScanner

Page two

b) 95% confidence internal for population mean life of the light bulbs is defined as fit suite) tc- ceitical vallie = loggg, s= 100 h264 X = 350 , put all this value -_in equation () we get 350 + 100 x 1.998 1350 -24, 979, 350 + 24,979 : - ( 325.5021, 3144.9.7 go) [325.502 CML | 374.949 we are 95% confident that ! population mean lies between i interval (325.50, 374.98 CS Scanned with hower range = 325.50 CamScanner

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