Question
Qing is getting married next Saturday at an outdoor ceremony in upscale westwood Country Club, Vienna. Virginia. In recent years, in the region, it has rained only 100 day s each year (365 days). Unfortunately, the weatherman has predicted rain for Saturday. When it actually rains, the weatherman correctly forecasts rain 80% of the time. When it doesn't rain, he incorrectly forecasts rain 20% of the time. Given the weatherman forecast for Saturday what is the probability of rain on Qing's wedding?
Explanation / Answer
Let us prepare a table for rain not rain first.
Normally prob for rain = 100/365
Prob for rain on wedding = Prob(predict and true) = 0.80
Rain Not Rain Predict 80% 20% Not predict 20% 80%