Thursday, December 10, 2009

Math Help With Probability Please!?

For a showing of a specific movie, an AMC theater estimates that 120 ppl will attend if it is not raining. It is is raining, the theater estimates that 200 people will attend. The meteorologist predicts at 70% chance of rain tomorrow. Determine the expected number of poeple who will attend the movie.



(the answer is 176 people.)



Math Help With Probability Please!?performing shows



Think of this as a weighted average.



the expected number of people will be the expected number of people if it is raining multiplied by the probability of rain plus the expected number of people if it is not raining multiplied by the probability of not raining.



Expected number of people



= 120 * P(not raining) + 200 * P(rain)



= 120 * 0.30 + 200 * 0.70



= 176



Math Help With Probability Please!?say yes opera theater



Take the difference between the two estimations (200 people if raining - 120 people if not raining = 80 people). The predictions differ by 80 people. Multiply 80 by the 70% chance of rain and you get 56. Add the 56 people to the 120 (or subtract it from the 200) and you get 176.

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