Jessica Salas,president of Salas Products,is reviewing the warranty policy for her company's new model of automobile batteries. Life tests performed on a sample of 100 batteries indicated: (1)an average life of 75 months,(2)a standard deviation of 5 months,and (3)a bell shaped battery life distribution.Approximately 68% of the batteries will last between ________________.
A) 70 and 80 months
B) 60 and 90 months
C) 65 and 85 months
D) 55 and 95 months
E) 60 and 100 months

Question

Quizplus · Accepted Answer

According to the empirical rule (68-95-99.7 rule) for a normal distribution, approximately 68% of the data falls within one standard deviation of the mean. Here, the mean is 75 months and the standard deviation is 5 months, so 68% of the batteries will last between 75 - 5 = 70 months and 75 + 5 = 80 months.

Jessica Salas,president of Salas Products,is Reviewing the Warranty Policy for Her