Question

An accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed is 19.0 hours. The distribution of the lives approximated a normal distribution. The standard deviation of the distribution was 1.2 hours. About 95% of the batteries failed between what two values?

Answer 1

Answer:

$(16.648, 21.352)$

Step-by-step explanation:

Let X be the accelerated life test on a large number of type-D alkaline batteries revealed that the mean life for a particular use before they failed

X is NOrmal with mean =19, sigma = 1.2

For 95% critical value = ±1.96

Margin of error = ±1.96*1.2

=±2.352

Confidence interval 95% = Mean ±2.352

=(16.648, 21.352)