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A box contains 9 balls marked 1 to 9. Four balls are drawn in succession
without replacement. Determine the probability that the four-digit number
formed is:
a. even
b. greater than 5000
c. an odd number less than 3000

 Mar 13, 2020
 #1
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a. Just look at the units digit to verify whether or not it's even. Essentially, it reduces the problem to the probability that the units digit is even. As such, the probability is just 4/9 (since there are 4 even numbers from 1-9)

 Mar 13, 2020

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