Question 339036: For which of the following values of N is 3N – 1 not a prime number?
(a) 1 (b) 2 (c) 3 (d) 4 (e) 6
Answer by nyc_function(2741)   (Show Source):
You can put this solution on YOUR website! A prime number can be divided, without a remainder, only by itself and by 1. For example, 17 can be divided only by 17 and by 1.
The only even prime number is 2. All other even numbers can be divided by 2.
We must replace N by every number on the list to find the one that does not yield a prime number.
Let N = 1, 2, 3, 4 and 6 individually in the given expression and simplify.
3N - 1
3(1) - 1 = 3 - 1 = 2...That's not it.
3N - 1
3(2) - 1 = 6 - 1 = 5...That's not it.
3N - 1
3(3) - 1 = 9 - 1 = 8...This is it! There is no need to go further with the process.
Understood?
The answer is CHOICE (C).
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