Answer:
Step-by-step explanation:
Let x be a random variable representing the life of a Brand Q car battery. With the mean and standard deviation given, then the Empirical Rule says the that
1) About 68% of the x values lie between 1 standard deviation below and above the mean.
2) About 95% of the x values lie between 2 standard deviations below and above the mean.
3) About 99.7% of the x values lie between 3 standard deviations below and above the mean.
From the information given,
mean = 36 months
Standard deviation = 4 months
Therefore,
1) 68% of all batteries will have a life between 36 - 4 = 32 months and 36 + 4 = 40 months.
2) 95% of all batteries will have a life between 36 - 2(4) = 28 months and 36 + 2(4) = 44 months.
