Classifying poor-quality streams. Refer to the previous exercise. Streams with IBI scores of less than 20 are classified as

“very poor,” while those with scores greater than 20 but less than 40 are classified as “poor.”

(a) Count the number of streams in the sample that are classified in these two categories, and use this result to compute an estimate of the proportion of streams that have either very poor or poor IBI scores.

(b) Can you use the confidence interval that you found in Exercise