Question

Cloud seeding has been studied for many decades as a weather modification procedure. The rainfall in acre feet from 20 clouds that were selected at random and seeded with silver nitrate follows: 18.0, 30.7, 19.8, 27.1, 22.3, 18.8, 31.8, 23.4, 21.2, 27.9, 31.9, 27.1, 25.0, 24.7, 26.9, 21.8, 29.2, 34.8, 26.7, 31.6

a) Is there evidence that the mean rainfall from seeded clouds exceeds 25 acre-feet? (1 pt)

b) If the true mean rainfall is 27 acre-feet, what is the probability of the test to indicate that the mean rainfall exceeds 25 acre-feet with a type-I error probability of 0.01? (1 pt)

c) If the true mean rainfall is 27.5 acre-feet, what sample size would be required if you want the test to correctly indicate 90% of the time that the mean rainfall exceeds 25 acre-feet with a type-I error probability of 0.01?

Answer 1