Question

two samples were taken of fish caught on small lake and are shown in the table below. it is estimated that the small lake fish population is roughly 1,000 fish. what is the average number of brown trout in the lake?

	small lake fish sample
rainbow trout	15	rainbow trout	11
brown trout	3	brown trout	1
largemouth bass	9	largemouth bass	11

43
80
160
333

Explanation:

Step1: Calculate total brown trout in samples

$3 + 1=4$

Step2: Calculate total fish in samples

$(15 + 3+9)+(11 + 1+11)=50$

Step3: Set up proportion

Let $x$ be the number of brown trout in the lake. The proportion is $\frac{4}{50}=\frac{x}{1000}$

Step4: Solve proportion for $x$

Cross - multiply: $50x = 4\times1000$, so $x=\frac{4\times1000}{50}=80$

Answer:

80