A probability forecast that calls for a "40 percent chance of rain" means that
A) there is a 40 percent chance that it will not rain within the forecast area.
B) there is a 40 percent chance that any random place in the forecast area will receive measurable rain.
C) it will rain on 40 percent of the forecast area.
D) it will rain during 40 percent of the time over the forecast area.

Question

Quizplus · Accepted Answer

A "40 percent chance of rain" means that out of 100 random samples of the forecast area with the same weather conditions, rain would occur in 40 of them, and not occur in 60 of them. Therefore, there is a 40 percent chance that any random place in the forecast area will receive measurable rain. Option A is incorrect because it implies that there is a 60 percent chance that it will rain, which is not the case. Option C is incorrect because it suggests that only 40 percent of the area is expected to receive rain, which is not necessarily true. Option D is incorrect because it suggests that it will rain for 40 percent of the forecast period, which is not specified in the given forecast.

A Probability Forecast That Calls for a "40 Percent Chance