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#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # A number line is divided by 10 evenly spaced tick marks.  Question banks Downloads My Bookmarks Reviews Important topics
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TAGS: Intern Joined: 06 Oct 2017
Posts: 9
Followers: 0

Kudos [?]: 3  , given: 2

A number line is divided by 10 evenly spaced tick marks. [#permalink]
1
KUDOS 00:00

Question Stats: 12% (00:01) correct 87% (01:01) wrong based on 8 sessions
A number line is divided by 10 evenly spaced tick marks. The length between each tick mark equals p, and p is a prime number.

Indicate all the possible lengths of the number line described above.

A- 10
B- 18
C- 22
D- 24
E- 27
F- 30
G- 36
H- 117
I- 130
[Reveal] Spoiler: OA GRE Instructor Joined: 10 Apr 2015
Posts: 2176
Followers: 65

Kudos [?]: 1992  , given: 20

Re: A number line is divided by 10 evenly spaced tick marks. [#permalink]
1
KUDOS
Expert's post
sameer93 wrote:
A number line is divided by 10 evenly spaced tick marks. The length between each tick mark equals p, and p is a prime number.

Indicate all the possible lengths of the number line described above.

A- 10
B- 18
C- 22
D- 24
E- 27
F- 30
G- 36
H- 117
I- 130

What's the source of this question?

I ask because I don't understand why B, D and E aren't among the answers.
If p = 3, then the measurements are 3, 6, 9, 12, 15, 18, 21, 24, 27 etc

Cheers,
Brent
_________________

Brent Hanneson – Creator of greenlighttestprep.com  GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4809
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 123

Kudos [?]: 1975  , given: 397

Re: A number line is divided by 10 evenly spaced tick marks. [#permalink]
2
KUDOS
Expert's post
There are 10 evenly spaced tick marks on a line. Say X is a tick mark.

X....X....X....X....X....X....X....X....X....X

So there are 9 spaces between the tick marks. If one space is length l. Then the length of line is $$9 \times l$$.

All the options that are multiples of 9 are correct. Except 36 because 36/9 is 4 which is not aprime number

Namely B, E and H

As Brent pointed out the answer seems to be a bit off. Or I misunderstood the question.
_________________

Sandy
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Manager Joined: 08 Dec 2018
Posts: 90
Followers: 0

Kudos [?]: 32 , given: 30

Re: A number line is divided by 10 evenly spaced tick marks. [#permalink]
sandy wrote:
There are 10 evenly spaced tick marks on a line. Say X is a tick mark.

X....X....X....X....X....X....X....X....X....X

So there are 9 spaces between the tick marks. If one space is length l. Then the length of line is $$9 \times l$$.

All the options that are multiples of 9 are correct. Except 36 because 36/9 is 4 which is not aprime number

Namely B, E and H

As Brent pointed out the answer seems to be a bit off. Or I misunderstood the question.

I am at one with this explanation, because the number line has 10 evenly spaced TICK MARKs ( NOT evenly spaced GAPs).
therefore, we have 9 GAPS* any prime number= our answers.
Intern Joined: 22 May 2019
Posts: 41
Followers: 0

Kudos [?]: 14 , given: 112

Re: A number line is divided by 10 evenly spaced tick marks. [#permalink]
I might be wrong. Here is my explanation. As we got total length will be 9P. P is a prime number, so we should check all prime numbers multiplied by 9. 9*1 won't work since 1 is not a prime number. So those numbers only divisible by 9 shouldn't be our answers. 9*2 works, so any numbers divisible by 18 will be answers. We get B, G. 9*3 will work. So numbers divisible by 27 will be our answers. We get E. I don't see any possible answers here when 9 is multiplied by prime numbers. So, B, E, G my answers. Please enlighten me!!! Re: A number line is divided by 10 evenly spaced tick marks.   [#permalink] 28 Jun 2019, 14:12
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