A light-bulb manufacturer advertises that average life for its light bulbs is 900 hours. A random sample of 15 of its light bulbs resulted in following lives in hours.
|
995
|
590
|
510
|
539
|
739
|
917
|
571
|
555
|
|
916
|
728
|
664
|
693
|
708
|
887
|
849
|
|
a. Find out x-bar and s for this data set.
b. At 10% significance level, do the data offer evidence that the mean life for company's light bulbs differs from the advertised mean? You might suppose the values for bulb life are normally distributed. Employ the traditional method to make your decision.