Question

making an inference
two samples of fish from a pond were analyzed. the second sample was taken six months after the first sample.

year 1	sample 1	sample 2
catfish	9	9
bass	8	6
all fish	20	20

which are valid inferences? check all that apply.

• the second sample shows the same amount of each type of fish in the pond.
• about twice as many trout were in the pond at the time the second sample was taken.
• about the same number of bass were found in the two samples.
• fewer bass were in the pond at the time the second sample was taken.
• about the same number of catfish were found in both samples.

Explanation:

1. For the first option: Sample 2 has different counts for trout, catfish, and bass, so it does not show the same amount of each fish type. This is invalid.
2. For the second option: Sample 1 has 3 trout, Sample 2 has 5 trout. 5 is not twice 3, so this inference is invalid.
3. For the third option: Sample 1 has 8 bass, Sample 2 has 6 bass. These numbers are relatively close, so this is a valid inference.
4. For the fourth option: The count of bass dropped from 8 to 6 in the samples, so we can infer fewer bass were in the pond when the second sample was taken. This is valid.
5. For the fifth option: Both samples have exactly 9 catfish, so this is a valid inference.

Answer:

• About the same number of bass were found in the two samples.
• Fewer bass were in the pond at the time the second sample was taken.
• About the same number of catfish were found in both samples.