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When a forest environment has changed because of logging or a forest fire, soil erosion from wind and water run-off is a big concern. A botanist is studying ceanothus plants, which are commonly used to help stabilize the soil on bare hillsides. The roots from the plants act like a wire mesh to keep the soil in place. One factor to consider for this type of plant is germination times. Germination time is measured from when a seed is hydrated (watered) until it produces its very first root.

Ceanothus plants will not germinate at room temperature. Cooler temperatures are required. Two batches of ceanothus seeds were watered and kept at the following cool temperatures (F) and their time until germination was measured (days). The boxplots are shown below (the F batch is the top boxplot). 

2 parallel Box Plots: x axis, scaled in tens, from 0 to 120. Values given are approximate. Top: Left whisker: 5 to 20. Box: 20 to 48 with vertical line at 32. Right whisker: 48 to 88. Outliers at 98 & 110. Bottom: Left whisker: 35 to 45. Box: 45 to 55 with vertical line at 50. Right whisker: 55 to 65.

  1. Describe the center, shape, spread, and outliers for the germination time of each batch of seeds.

    Center refers to the typical germination times, so use the mean or median. Descriptions of shape include words like symmetric, uniform, or skewed. To describe the spread, use the standard deviation or IQR.

    Which batch was more consistent?

  2. How might this information be useful to firefighters who plant ceanothus seeds to prevent erosion after a fire?

    Assuming that the firefighters can spread thousands of seeds, what would be better weather conditions, F or F? Why?