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

Redeem

For positive integer values of n, the operation . . . . .

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Legendary Member
Posts: 2898
Joined: Thu Sep 07, 2017 2:49 pm
Thanked: 6 times
Followed by:5 members

For positive integer values of n, the operation . . . . .

by Vincen » Wed Jan 03, 2018 11:59 am
For positive integer values of n, the operation n# is defined as the sum of all integers from 1 to n, inclusive. For example, 4# = 1 + 2 + 3 + 4 = 10. If 15# - 14# = k#, what is the value of k#?

A. 1
B. 4
C. 5
D. 14
E. 15

The OA is the option E.

Is there an easy way to solve this PS question without making the whole calculation? I need your help experts. Thanks in advanced.
Top
Source: — Problem Solving |
User avatar
GMAT Instructor
Posts: 555
Joined: Wed Oct 04, 2017 4:18 pm
Thanked: 180 times
Followed by:12 members

Answer

by EconomistGMATTutor » Wed Jan 03, 2018 12:58 pm
Hello Vincen.

Let's take a look at your question.

We have to solve 15#-14#=k#. But, we have to notice that 15# = 15 + 14#.

Now, we can rewrite 15#-14#=k# as follows: $$ k\# = 15\#-14\#\ =\ 15\ +\ 14\#\ -\ 14\#\ =\ 15 .$$ Therefore, the correct answer is E.

I hope this explanation may help you.

I'm available if you'd like a follow-up.

Regards.
GMAT Prep From The Economist
We offer 70+ point score improvement money back guarantee.
Our average student improves 98 points.

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