A claim about all members of a group is a generalization: it extends a result beyond what was studied. Check how the participants entered the study, not only how they were split into groups. Random assignment helps test cause; random sampling helps extend a result to a population. The trap is treating randomly assigned as if it meant randomly selected.
Hints
- Hint 1
The target population is the whole group a conclusion describes. Compare any tomato plant with the plants the horticulturist studied. Could the conclusion include plants from other varieties or growing conditions?
- Hint 2
Random sampling uses chance to choose which plants enter a study. Random assignment uses chance to decide what treatment those plants receive. Which random step does the question describe?
Step-by-step
Check who the experiment represents
Step 1Identify the group named in the conclusion
No Desmos needed. The issue is who the result can cover, not a calculation. The claim says any tomato plant, so its target population, the whole group the claim describes, includes plants of other seed varieties and plants grown in other settings.
- Step 2
Check which plants could enter the study
The plants were all from the same seed variety and the same greenhouse. They were not randomly selected from tomato plants grown under varied conditions, so those other plants had no chance to be included. That limits how far the result can be extended.
- Step 3
Separate the cause test from the population claim
Random assignment split the selected plants between fertilizer and no fertilizer, helping test whether fertilizer caused the difference for the plants studied. It is not random sampling from all tomato plants. So the study does not justify extending the average increase to any tomato plant: the plants were not randomly selected from that broader population. Choice D.