A student wants to determine if different types of soil, a and b, affect the propagation of african violets. One hundred leaves from the same variety of african violet were selected. The leaves were then randomly assigned to 50 pots with type a soil and the remaining leaves were put into the 50 pots with type b soil. All of the pots were given the same amount of water and arranged in 10 rows of 10 pots near a window for light. The 50 pots with type a soil were placed closest to the window. At the end of two months, the pots with type a soil had the greatest number of pots with new growth, so the student concluded that soil type a was more effective that soil type b. Is this a valid conclusion?.

Sunlight is a necessary element for plant growth, therefore only type A potting soil is placed near a window, thus causing new growth of the African violet.

The type of soil did not affect this experiment, because the treatment in pot B could not be known whether the pot was exposed to sunlight or not. If the experimental variables are focused on soil type and other variables can be controlled, then this experiment can find out whether soil type affects the growth of African violets. So, the results of this experiment are still biased.

Learn more about experiment types of soil at https://brainly.com/question/3574802

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