How Many Integers

This topic has expert replies
User avatar
Master | Next Rank: 500 Posts
Posts: 154
Joined: Wed May 21, 2014 4:29 am
Thanked: 8 times
Followed by:1 members

How Many Integers

by talaangoshtari » Sun May 01, 2016 1:43 am
How many integers between 1 and 300, inclusive, can be expressed as x^y, where x and y are integers greater than 1?

A.17
B.23
C.24
D.30
E.31

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Sun May 01, 2016 3:14 am
talaangoshtari wrote:How many integers between 1 and 300, inclusive, can be expressed as x^y, where x and y are integers greater than 1?

A.17
B.23
C.24
D.30
E.31
2²...2� --> 7 options
Note:
SInce 4, 8 and 16 can be written as 2², 2³, and 2�, respectively, the 7 options above include all of the viable options for 4, 8 and 16.

3²...3� --> 4 options
Note:
Since 9 can be written as 3², the 4 options above include all of the viable options for 9.

5² and 5³ --> 2 options
6² and 6³ --> 2 options
7², 10², 11², 12², 13², 14², 15², 17² --> 8 options

Total options = 7+4+2+2+8 = 23.

The correct answer is B.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3