Question

1. The life span of 100 W light bulbs manufactured by a particular company follows a normal distribution with a standard deviation of 120 hours, and its average life time is guaranteed for a minimum of 800 hours. A delivery of 10,000 of light bulbs is sent to a wholesale store, and the quality control staff in the store randomly selected 50 bulbs to test the life time. The average life time of the sample is found out to be 760 hours, with a standard deviation of 145 hours.  

(1)  What are the sample and population of the study? (Please describe in context words for the specific study, don’t use general definition).  

(2)  

There are a few numbers given from the problem, identify if they are parameter or statistic. What symbol do we use to denote each of the statistics or parameters?  

Values	Statistic or parameter	What symbol?
10,000
50
800
120
760
145

Answer 1

S6 solution Let, X. The life span of light bulbs And XnNCu=800, 6² = (1207) 1) The sample is The quality control staff in the store selected so bulbs to test the life time. Land Population of the study: A delivery of loooo of light bulbs is sent a whole sale stase with population 800 hours randomly to bean 2) consider the following table.

Values Statistic or Parameter Symbols Parameter 10000 Statistic n 800 Parameter Parameter 120 Statistic X 145 Statistic 5