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 95% 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

Approximately 95% of the data in a normal distribution falls within two standard deviations from the mean. Here, the mean is 75 months and the standard deviation is 5 months. So, 75 ± 2(5) = 65 to 85 months.

Jessica Salas, President of Salas Products, Is Reviewing the Warranty