# 211_Section7_4problem.pdf - Section 7.4 Probability and...

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Section 7.4 Probability and Counting Techniques Modeling Probability: Equally Likely Outcomes In an experiment in which all outcomes are equally likely, the probability of an event E is given by: ) ( ) ( outcomes of number Total outcomes favorable of Number ) S n E n E P Example 1 A bag contains four red marbles, three green marbles, two white ones, and one purple one. If five marbles are grabbed, then find each of the following probabilities. 2. She has no red marbles 8. She has no more than one white marble Example 2 26. A standard piano keyboard has 88 different keys. Find the probability that a cat, jumping on 4 keys in sequence and at random (possibly with repetition) will strike the first four notes of Beethoven’s Fifth Symphony? 30. The Sad State Lottery requires you to select a sequence of three different numbers from 0 through 49. (Order is important). You are a Winner if your sequence agrees with that in the drawing, (