Suppose the distribution of X, the number of Ligula intestinalis worms infecting a randomly selected host from the Rutilus rutilus population, has the following probability distribution:

x	0	1	2	3
P(X=x)	0.18	0.34	0.23	0.25

The expected number of Ligula intestinalis worms in a fish from the Rutilus rutilus population is

1.00

1.50

1.55

1.68

Question 2

The standard deviation of the number of Ligula intestinalis worms in a fish from the Rutilus rutilus population is

1.052

1.108

1.377

1.736

Question 3

We are often interested in the prevalence of parasitic infection, where prevalence is defined as the probability a randomly selected individual from the host species has at least one parasite. Based on the table of probabilities, what is the prevalence of Ligula intestinalis in the Rutilus rutilus population?

0.18

0.34

0.75

0.82

Question 4

A sample of 10 fish from the Rutilus rutilus population is taken. The distribution of the number of fish infected with Ligula intestinalis in the sample is

Binomial(10,0.25)

Normal(8.2,1.21)

Normal(0.82,0.12)

Binomial(10,0.82)

Question 5

The probability that 6 or fewer fish are infected with Ligula intestinalis in the sample from Question 4 is

0.0670

0.0883

0.2508

0.6177

Question 6

A sample of 100 fish from the Rutilus rutilus population is taken. The distribution of the number of fish infected with Ligula intestinalis in the sample is approximately

Binomial(82,0.82)

Normal(82,0.89)

Normal(82,3.84)

Normal(0.82,0.038)

Question 7

The Ligula intestinalis parasites can sometimes be difficult to identify in hosts. Suppose we correctly identify an infected host as having one or more parasites only 80% of the time. What is the probability that a randomly selected fish from the Rutilus rutilus population is identified as being infected with Ligula intestinalis?

0.145

0.164

0.656

0.921

Question 8

A randomly selected fish from the Rutilus rutilus population is inspected and no Ligula intestinalis parasites are identified. What is the probability that this fish has no Ligula intestinalis parasites?

0.164

0.344

0.523

0.754