guerrero wrote:How many positive integers less than 30 are either a multiple of 2, an odd prime number, of the sum of a positive multiple of 2 and an odd prime?
A. 29
B. 28
C. 27
D. 25
E. 23
OA A
How to tackle ?
There are
29 positive integers that are less than 30 (1, 2, 3, ... 28, 29)
Multiples of 2: 2, 4, 6, 8, ... (all even numbers)
Sum of a positive multiple of 2 and an odd prime: 3+2, 3+4, 3+6, 3+8, . . .
In other words, 5, 7, 9, 11, 13 (all odd numbers
> 5)
At this point, we've accounted for all positive integers less than 30 EXCEPT for 1 and 3
Since 3 is a prime number, it is also accounted for.
The only number NOT accounted for is 1.
So, the answer is
29 - 1 = [spoiler]28 = B[/spoiler]
Cheers,
Brent
