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 95.44% of the batteries failed between what two values?
a. 8.9 and 18.9
b. 12.2 and 14.2
c. 14.1 and 22.1
d. 16.6 and 21.4

d. 16.6 and 21.4

Step-by-step explanation:

The Empirical Rule states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95.44% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we have that:

Mean = 19

Standard deviation = 1.2

About 95.44% of the batteries failed between what two values?

Within 2 standard deviations of the mean

19 - 2*1.2 = 16.6

19 + 2*1.2 = 21.4

So the correct answer is:

d. 16.6 and 21.4

i think there was a typo. you wrote pat brings 3 quarts of ice-cream to the party. each serving of ice-cream is 1 6 quart. how many total servings of ice-cream does pat bring to the party? i think the bold is supposed to be 1/6. so 1 quart of ice cream = 6 servings. 6 * 3 = 18.

answer: the answer is e

step-by-step explanation: