GRE Prep Club Daily Prep
Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized
for You
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
How many positive integers less than 30 are either a multipl
[#permalink]
23 Apr 2020, 10:22
23 Apr 2020, 10:22
Expert Reply
3
Bookmarks
00:00
Question Stats:
38% (01:53) correct
61% (02:22) wrong based on 18 sessions
Hide Show timer Statistics
How many positive integers less than 30 are either a multiple of 2, an odd prime number, or the sum of a positive multiple of 2 and an odd prime?
A. 29
B. 28
C. 27
D. 25
E. 23
A. 29
B. 28
C. 27
D. 25
E. 23
Retired Moderator
Joined: 10 Apr 2015
Posts: 6218
Given Kudos: 136
Re: How many positive integers less than 30 are either a multipl
[#permalink]
23 Apr 2020, 12:45
23 Apr 2020, 12:45
3
1
Bookmarks
Carcass wrote:
How many positive integers less than 30 are either a multiple of 2, an odd prime number, or the sum of a positive multiple of 2 and an odd prime?
A. 29
B. 28
C. 27
D. 25
E. 23
A. 29
B. 28
C. 27
D. 25
E. 23
Multiples of 2: 2, 4, 6, 8, 10, . . .26, 28
Sum of a positive multiple of 2 and an odd prime
3 is the smallest ODD prime
So, let's add multiples of 2 to 3.
We get: 3 + 2, 3 + 4, 3 + 6, 3 + 8, etc
Evaluate to get: 5, 7, 9, 11, . . . 27, 29
At this point, our list of numbers includes 2 as well as all integers from 4 to 29
All we're missing is 1 and 3
An odd prime number
3 is odd, so, now our list becomes: 2, 3, 4, 5, 6, . . . 27, 28, 29
So, the ONLY value that is NOT in the list is 1 (1 is NOT prime)
So, there are 28 numbers that meet the given conditions.
Answer: B
Cheers,
Brent
Re: How many positive integers less than 30 are either a multipl
[#permalink]
17 Apr 2024, 16:06
17 Apr 2024, 16:06
Hello from the GRE Prep Club BumpBot!
Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
Thanks to another GRE Prep Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).
Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
