1. The amount of pollutants that are found in waterways near large cities is normally distributed with mean 8.6 ppm and standard deviation 1.4 ppm. 17 randomly selected large cities are studied. Round all answers to 4 decimal places where possible.

1. What is the distribution of XX? XX ~ N(,)
2. What is the distribution of xx? xx ~ N(,)
3. What is the probability that one randomly selected city's waterway will have more than 7.7 ppm pollutants?
4. For the 17 cities, find the probability that the average amount of pollutants is more than 7.7 ______ppm.
5. For part d), is the assumption that the distribution is normal necessary? Yes____No
6. Find the IQR for the average of 17 cities. Q1 =_____ ppm Q3 = _____ ppm IQR: ______ppm

2. The amount of time that people spend at Grover Hot Springs is normally distributed with a mean of 70 minutes and a standard deviation of 14 minutes. Suppose one person at the hot springs is randomly chosen. Let X = the amount of time that person spent at Grover Hot Springs . Round all answers to 4 decimal places where possible. a. What is the distribution of X? X ~ N(,) b. Find the probability that a randomly selected person at the hot springs stays longer then 85 minutes. c. The park service is considering offering a discount for the 4% of their patrons who spend the least time at the hot springs. What is the longest amount of time a patron can spend at the hot springs and still receive the discount? _____minutes. d. Find the Inter Quartile Range (IQR) for time spent at the hot springs. Q1: ____minutes Q3: ______ minutes IQR: ______ minutes

3. 70 adults with gum disease were asked the number of times per week they used to floss before their diagnoses. The (incomplete) results are shown below:

# of times floss per week	Frequency	Relative Frequency	Cumulative Frequency
0	13	0.1857	13
1	8	0.1143	21
2		0.1	28
3	5	0.0714	33
4	4	0.0571	37
5	10		47
6	11	0.1571	58
7	12	0.1714

a. Complete the table (Use 4 decimal places when applicable)

b. What is the cumulative relative frequency for flossing 3 times per week? %

Find the area of the shaded region under the standard normal distribution to the left of the given z-score. Round your answer to four decimal places. -2 O 3 2 1.94 P(2