MATA67H3 Lecture 5: w5
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Let e be the event that the rst two tosses are the same and f be the event that the last two tosses are the same. A. n(e and f ) = n(e f ) Now we can calculate the probability p (e or f ): Theorem (the sum rule) if e and f are events in an experi- ment then the probability that e or f occurs is given by: P (e or f ) = p (e) + p (f ) p (e and f ) Let e5 be the event that at least one die shows a 5. E8 the dice sums to 8. P(e5 or e8) = p(e5) + p(e8) - p(e5 + e8) Given a bag of 3 red marbles, 5 black marbles and 8 green marbles select one marble and then a second. Not 3/16 now to calculate the probability of the second marble being red given that the 1st marble is red 2/15.
