Weed be gone (3.5, 3.6) A biologist would like to determine which of two brands of weed killer, X or Y, is less likely to harm the plants in a garden at the university. Before spraying near the plants, the biologist decides to conduct an experiment using 24 individual plants. The biologist chooses the 12 healthiest-looking plants and then flips a coin. If it lands heads up, apply Brand X weed killer to these plants and Brand Y weed killer to the remaining 12 plants. If it lands tails up, do the opposite. What flaw in this study makes it impossible to determine which brand of weed killer is better? Explain.