Question

Ecotoxicological survival study. In the Journal of Agri- cultural, Biological and Environmental Sciences (Sept., 2000), researchers evaluated the risk posed by hazardous pollutants using an ecotoxicological survival model. For one experiment, 20 guppies (all the same age and size) were released into a tank of natural seawater polluted with the pesticide dieldrin. Of interest is Y, the number of guppies surviving after 5 days. The researchers esti- mated that the probability of any single guppy surviving was .60.

1. Demonstrate that Y has a binomial probability distribu- tion. What is the value of p?

2. Find the probability that Y = 7.

3. Find the probability that at least 10 guppies survive.

Answer 1