BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Which of the following is NOT a factor of 20!?

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Problem Solving |

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 3008
Joined: Mon Aug 22, 2016 6:19 am
Location: Grand Central / New York
Thanked: 470 times
Followed by:34 members

Re: Which of the following is NOT a factor of 20!?

by Jay@ManhattanReview » Thu Aug 06, 2020 12:00 am
BTGmoderatorDC wrote: ↑
Wed Aug 05, 2020 5:35 pm
 Which of the following is NOT a factor of 20!?

I. 29
II. 85
III. 121

A. I only
B. II only
C. III only
D. I and II
E. I and III

OA E

Source: Magoosh
We know that 20! = 1.2.3....20.

Let's take each statement one by one.

I. 29: Since 29 is a prime number and is greater than 20, we see that 29 is NOT a factor of 20!.

II. 85: Note that 85 = 17*5. Since 5 and 17 are less than 20, 20! has at least one 5 and 17, 85 is factor of 20!.

III. 121: Note that 121 = 1*11. Since 20! has only one 11, 20! does not have 121 as a factor of 20!.

Correct answer: E

Hope this helps!

-Jay
_________________
Manhattan Review GMAT Prep

Locations: GMAT Prep Phoenix | GRE Prep West Palm Beach | GMAT Prep Asia | SAT Prep St. Louis | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Top

GMAT/MBA Expert

User avatar
GMAT Instructor
Posts: 8083
Joined: Sat Apr 25, 2015 10:56 am
Location: Los Angeles, CA
Thanked: 43 times
Followed by:29 members

Re: Which of the following is NOT a factor of 20!?

by Scott@TargetTestPrep » Mon Aug 10, 2020 10:25 am
BTGmoderatorDC wrote: ↑
Wed Aug 05, 2020 5:35 pm
 Which of the following is NOT a factor of 20!?

I. 29
II. 85
III. 121

A. I only
B. II only
C. III only
D. I and II
E. I and III


OA E

Solution:

Since 20! does not contain a prime factor of 29, 29 is not a factor of 20!

Since 85 = 17 x 5, and 20! contains both prime factors of 17 and 5, 85 is a factor of 20!.

Since 121 = 11^2, and 20! does not have 2 prime factors of 11, 121 is not a factor 20!.

Answer: E

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

ImageImage
Top
Post new topic Post Reply
• Page 1 of 1