According to a research study on wildlife ecology and conservation, the average level of mercury uptake in wading birds in the Everglades Florida has declined over the past several years. Ten years ago, the average level was 15 parts per million (ppm). For testing whether the average level today (denoted by ) is less than 15 ppm, we set up H0 : = 15 versus Ha : < 15.

a) Describe a Type I error of this test using the context.

b) Describe a type II error of this test using the context.