Question 1106178
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There are 100 different numbers, 0 through 99; each one presumably equally likely.<br>
(a) There are 19 numbers greater than 80: 81, 82, ..., 98, and 99.  So the probability that the number is greater than 80 is 19/100 = 0.19.<br>
(b) There are 34 numbers that are multiples of 3: 0, 3, 6, 9, ..., 96, and 99.  So the probability that the number is a multiple of 3 is 34/100 = 0.34.