Hi there folks,
I'm just beginning to prepare for the GMAT by using the Princeton Math Workout book (published 1998) and have a question that doesn't make sense to me.
Here it is,
How many positive integers less than 28 are prime numbers, odd multiples of 5, or the sum of a positive multiple of 2 and a positive multiple of 4.
I put the answer and explanation, as well as my question further down in case you want to try to figure it out:
(d) is the correct answer. Here is the explanation for why:
The prime numbers are: 2,3,5,7,11,13,17,19,23 (total 9 )
The odd multiples of 25 are: 5,15,25 (total 3)
The numbers that can be expressed as the sum of a positive multiple of 2 and a postive multiple of four are all the even numbers over 4: 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26 (total 11)
So how can (d), which is 22, be the correct answer?
I apologize if I've overlooked a *really* obvious error--but I can't find it anywhere!
Any shedable light would be warmly received indeed,
That's because 5 is common to both prime numbers and odd multiples of 5.
Hope that helps.
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