3.1 What is meant by the term ecosystem (line 3)?   (2)

  Use only if needed

1.2 Water pollution can occur if sewage enters a river. Explain the biological consequences of sewage pollution on a river ecosystem. (6)

Pollution can occur in the atmosphere and in rivers. Carbon monoxide can pollute the atmosphere.   1.1 Describe the effects of carbon monoxide pollution on humans.   (3)

3.4 Suggest how scientists are able to find the percentage of coral that has died in a section of the reef. (3)

Use the normal approximation to find the indicated probability. The sample size is n, the population proportion of successes is p, and X is the number of successes in the sample. n = 83, p = 0.35: P(X ≤ 27)

The following histograms each illustrate a sample. Which sample can be treated as approximately normal?

The Australian sheep dog is a breed renowned for its intelligence and work ethic. It is estimated that 45% of adult Australian sheep dogs weigh 65 pounds or more. A sample of 14 adult dogs is studied. What is the standard deviation of the number of dogs who weigh 65 lb or more?

A sample of size 40 will be drawn from a population with mean 98 and standard deviation 24. Find the 21st percentile of .

A researcher wants to construct a 99% confidence interval for the proportion of elementary school students in Seward County who receive free or reduced-price school lunches. What sample size is needed so that the confidence interval will have a margin of error of 0.07?