Answer:
Step-by-step explanation:
The fish population after t years can be modeled by the following equation:
In which F(0) is the initial population and r is the constant rate of decay.
Year one the fish population was 18000
This means that
In year three the fish population was 8000 fish.
Two years later, so
So
The empirical rule you're referring to is the 68-95-99.7 rule, which asserts that for a normal (bell-shaped) distribution, approximately 68% of the distribution lies within 1 standard deviation of the mean; 95% lies within 2 standard deviations of the mean; and 99.7% lies within 3 standard deviations of the mean.
Let be the random variable denoting vehicle speeds along this highway. We want to find
. To use the rule, we need to rephrase this probability in terms of the mean and standard deviation.
Notice that , and
. In other words, 61 and 79 both lie exactly 3 standard deviations away from the mean, so
.