Dead trees On the west side of Rocky Mountain National Park, many mature pine trees are dying due to infestation by pine beetles. Scientists would like to use sampling to estimate the proportion of all pine trees in the area that have been infected.

(a) Explain why it wouldn’t be practical for scientists to obtain an SRS in this setting.

(b) A possible alternative would be to use every pine tree along the park’s main road as a sample. Why is this sampling method biased?

(c) Suppose that a more complicated random sampling plan is carried out, and that 35% of the pine trees in the sample are infested by the pine beetle. Can scientists conclude that exactly 35% of all the pine trees on the west side of the park are infested? Why or why not?