Query ; Prime Numbers

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soni_pallavi: Master | Next Rank: 500 Posts; Posts: 107; Joined: Tue Jun 05, 2012 3:25 amFollowed by: 13 members; Thanked: 1 times

by soni_pallavi » Thu Nov 22, 2012 8:56 am

Q1

If p is a prime number greater than 2, what is the value of p??

1)There are a total of 100 prime numbers between 1 and p+1.

2)There are a total of p prime numbers between 1 and 3912.

Ans D

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Source: Beat The GMAT — Data Sufficiency | Thu Nov 22, 2012 8:56 am

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Thu Nov 22, 2012 9:27 am

soni_pallavi wrote:Q1

If p is a prime number greater than 2, what is the value of p?

1)There are a total of 100 prime numbers between 1 and p+1.
2)There are a total of p prime numbers between 1 and 3912.

Target question: What is the value of p?

Statement 1: There are a total of 100 prime numbers between 1 and p+1
In other words, p is the 100th prime number.
So, if we begin listing primes (2,3, 5, 7, 11, 13,..), the 100th prime on our list will equal p.
Since we could use statement 1 to definitively determine the value of p, statement 1 is SUFFICIENT

Statement 2: There are a total of p prime numbers between 1 and 3912.
Well, we could list every prime number between 1 and 3912, and then count how many primes are in the list. This would give us the value of p.
Since we could use statement 2 to definitively determine the value of p, statement 2 is SUFFICIENT

Answer = D

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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