Question

The amount of pollutants that are found in waterways near large cities is normally distributed with mean 8.8 ppm and standard deviation 1.8 ppm. 12 randomly selected large cities are studied. Round all answers to 4 decimal places where possible.

What is the distribution of X X ? X X ~ N(,)

What is the distribution of ¯ x x¯ ? ¯ x x¯ ~ N(,)

What is the probability that one randomly selected city's waterway will have more than 9.8 ppm pollutants?

For the 12 cities, find the probability that the average amount of pollutants is more than 9.8 ppm.

For part d), is the assumption that the distribution is normal necessary? Yes No

Find the IQR for the average of 12 cities.

Q1 = ppm

Q3 = ppm

IQR: ppm

Answer 1