GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 16 Oct 2019, 18:36

Close

GMAT 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

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

P is a prime number. If 6p is between 15 and 95

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Intern
Intern
avatar
Joined: 18 Feb 2011
Posts: 33
GPA: 3.91
P is a prime number. If 6p is between 15 and 95  [#permalink]

Show Tags

New post 05 Feb 2012, 23:33
1
1
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

85% (01:56) correct 15% (01:55) wrong based on 153 sessions

HideShow timer Statistics

P is a prime number. If 6p is between 15 and 95, which of the following can be a value of 7p + 2?

A. 15
B. 79
C. 121
D. 65
E. 21
Manager
Manager
avatar
B
Joined: 31 Jan 2012
Posts: 69
Re: P is a prime number. If 6p is between 15 and 95  [#permalink]

Show Tags

New post 06 Feb 2012, 01:18
1
1
[3,5,7,11,13] are prime numbers that fits this equation 15< 6X <95. Afterwards subtract 2 from all the answer n see if it's divisible by 7. Therefore A and E are out. Leaves out with B C D.
B =11
C =17
D = 9
Only 11 is the set of prime numbers that fit between 15 and 95. Therefore 79 is the answer.
Intern
Intern
avatar
Joined: 05 Jan 2012
Posts: 43
Schools: Wharton '15
WE: Sales (Internet and New Media)
Re: P is a prime number. If 6p is between 15 and 95  [#permalink]

Show Tags

New post 06 Feb 2012, 01:51
Answer is B- of the prime numbers between 15 & 95, only 11 fits into one of the answer choices
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58381
Re: P is a prime number. If 6p is between 15 and 95  [#permalink]

Show Tags

New post 06 Feb 2012, 01:58
nafishasan60 wrote:
P is a prime number. If 6p is between 15 and 95, which of the following can be a value of 7p + 2?

A. 15
B. 79
C. 121
D. 65
E. 21


15<6p<95 --> the minimum value of prime number p is 3 (6*3=18>15) and the maximum value is 13 (6*13=84<95 and 6*17>95). So, possible values of p are: 3, 5, 7, 11, and 13.

We should have 7p+2={answer choice} --> 7p={answer choice}-2;

Answer choices which are multiples of 7 after we subtract 2 are 79 (B), 121 (C) and 65 (D) but only (79-2)/7 yields a prime number from our range: 11. 121 also yields a prim number 17, (121-2)/7=17=prime, but 17 is out of our range.

Answer: B.
_________________
Veritas Prep GMAT Instructor
User avatar
V
Joined: 16 Oct 2010
Posts: 9705
Location: Pune, India
Re: P is a prime number. If 6p is between 15 and 95  [#permalink]

Show Tags

New post 06 Feb 2012, 02:10
2
1
nafishasan60 wrote:
P is a prime number. If 6p is between 15 and 95, which of the following can be a value of 7p + 2?

A. 15
B. 79
C. 121
D. 65
E. 21


Even though you already have the solution, let me point out the takeaway from this question.

"which of the following can be..." questions are generally best done by using the options. Use the options to find the one which satisfies all conditions.

We see that the format we are looking for is 7p + 2.
When you subtract 2 from option A, you get 13 - not a multiple of 7. Ignore.
When you subtract 2 from option B, you get 77. It is a multiple of 7. Let's check it. p = 11 which is prime. Good. 6p = 66 which is between 15 and 95. Very good. All conditions satisfied so answer is (b)
_________________
Karishma
Veritas Prep GMAT Instructor

Learn more about how Veritas Prep can help you achieve a great GMAT score by checking out their GMAT Prep Options >
Target Test Prep Representative
User avatar
D
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8069
Location: United States (CA)
Re: P is a prime number. If 6p is between 15 and 95  [#permalink]

Show Tags

New post 31 Oct 2018, 18:22
nafishasan60 wrote:
P is a prime number. If 6p is between 15 and 95, which of the following can be a value of 7p + 2?

A. 15
B. 79
C. 121
D. 65
E. 21


If p is 3, then 6p is 18.

If p is 13, then 6p is 78.

So p must be between 3 and 13, inclusive, and thus 7p + 2 must be between 23 and 93, inclusive. We see that both answer choices B 79 and D 65 are between 23 and 93.

If 7p + 2 = 79, then 7p = 77 and p = 11.

If 7p + 2 = 65, then 7p = 63 and p = 9.

Since p = 11 is a prime (and p = 9 is not a prime), then 7p + 2 = 79.

Alternate Solution:

Let’s test each answer choice:

A) 7p + 2 = 15

If 7p + 2 = 15, then 7p = 13 and p is not an integer.

B) 7p + 2 = 79

If 7p + 2 = 79, then 7p = 77 and p = 11. We see that 6p = 66 is between 15 and 95; therefore B is the correct choice.

Answer: B
_________________

Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

GMAT Club Bot
Re: P is a prime number. If 6p is between 15 and 95   [#permalink] 31 Oct 2018, 18:22
Display posts from previous: Sort by

P is a prime number. If 6p is between 15 and 95

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





cron

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne