How can I solve this question

This topic has expert replies
Source: — Problem Solving |

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 » Sat Nov 10, 2012 5:44 pm
M is the sum of the reciprocals of the consecutive integers from 201 to 300, inclusive. Which of the following is true?

(A) 1/3 < m < 1/2
(B) 1/5 < m < 1/3
(C) 1/7 < m < 1/5
(D) 1/9 < m < 1/7
(E) 1/12 < m < 1/9
If all of the 100 values were 1/300, the result would be the following sum:
100(1/300) = 1/3.
If all of the 100 values were 1/200, the result would be the following sum:
100(1/200) = 1/2.
There is no value in m less than 1/300 or greater than 1/200.
Thus, the sum of m -- 1/201 + 1/202 +...+ 1/300 -- must be BETWEEN 1/3 and 1/2.

The correct answer is A.
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