Question

Dog Bites to Postal Workers For a certain urban area, in a random sample of 5 months, an average of 28 mail carriers were bitten by dogs each month. The standard deviation of the sample was 3. Find the 90% confidence interval of the true mean number of mail carriers who are bitten by dogs each month. Assume the variable is normally distributed.

Answer 1

Answer: 90% confidence interval is (25.8,30.2).

Step-by-step explanation:

Since we have given that

n = 5

Mean = 28

Standard deviation = 3

It is a 90% confidence interval , so, z = 1.64

We need to find the interval.

so, it would be

$x\pm z(\dfrac{\sigma}{\sqrt{n}})\\\\=28\pm 1.64\times (\dfrac{3}{\sqrt{5}})\\\\=28\pm 2.2\\\\=(28+2.2,28-2.2)\\\\=(25.8,30.2)$

Hence, 90% confidence interval is (25.8,30.2).