# An economist wishes to estimate the average

Question # 00612185 Posted By: rey_writer Updated on: 11/03/2017 09:15 AM Due on: 11/03/2017
Subject Mathematics Topic Probability Tutorials:
Question

Probability

1. An economist wishes to estimate the average family income in a certain population. The population standard deviation is known to be \$4,500, and the economist uses a random sample of size = 225.

a. What is the probability that the sample mean will fall within \$800 of the population mean?

b. What is the probability that the sample mean will exceed the population mean by more than \$600.

Please provide full detail including how the z-table lookup is determined.

2. The article "Reliability of Domestic Waste Biofilm Reactors" (J. of Envir. Engr., 1995: 785-790) suggests that substrate concentration (mg/cm^3) of influent to a reactor is normally distributed with &#61549; = 0.30 and &#61555; = 0.06.

a. What is the probability that the concentration exceeds 0.40?

b. What is the probability that the concentration is at most 0.25?

c. How would you characterize the largest 10% of all concentration levels?