A password for a computer is six digits from 0 and 9. The six digit number is a prime number. What is the approximate probability that the last digit is a 3?\nOptions:\n(A) 1/4\n(B) 1/6\n(C) 1/10\n(D) 1/20\n(E) 1/50 Hmmm, my stream of consciousness:
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If the last digit is 0, 2, 4, 6, or 8, the number is even and therefore not prime. If the last digit is 5, the number is divisible by 5 and therefore not prime. The only possibilities are 1, 3, 7, and 9. So the probability is approximately 1/4 (answer A). We say approximately because there is a certain degree of randomness in the distribution of prime numbers. So, the answer is (A).
Assistant