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.

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

In a sequence of 13 consecutive integers, all of which are [#permalink]
18 Jun 2006, 21:58

00:00

A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct
0% (00:00) wrong based on 0 sessions

In a sequence of 13 consecutive integers, all of which are less than 100, there are exactly 3 multiples of 6. How many integers in the sequence are prime?

(1) Both of the multiples of 5 in the sequence are also multiples of either 2 or 3.

(2) Only one of the two multiples of 7 in the sequence is not also a multiple of 2 or 3.

St1:
1-13: Out. Only two multiple of 6
6-18: 3 multiples of 6, two multiples of 5 are also multiples of 2 or 3. --> 4 primes
12-24: 3 multiples of 6, 2 multiples of 5 are also multiples of 2 or 3 --> 4 primes

Should always end up with 4 primes. Sufficient.

St2:
6-18: 3 multiples of 6, two muliples of 7, and one is not a multiple of 2/3 --> 4 primes

Can't think of any other series that satisfies the criteria set in st2. Should be be just 6-18. In any case, the number of primes integers in this set = 4. Sufficient.

Re: DS - Mixed Bag [#permalink]
19 Jun 2006, 08:02

shobhitb wrote:

In a sequence of 13 consecutive integers, all of which are less than 100, there are exactly 3 multiples of 6. How many integers in the sequence are prime?

(1) Both of the multiples of 5 in the sequence are also multiples of either 2 or 3.

(2) Only one of the two multiples of 7 in the sequence is not also a multiple of 2 or 3.

Is this a plugging problem? this could take time. Any way to use number theory here to shorten the time? (for e.g. divisibility of last 2 digits, prime factors etc.) _________________