In the sequence, r, s, t, if each term after the first is x more than the previous term, what is the average of r, s, and t in terms of r and x?
A) r + x
B) r + x/3
C) r + 2x/3
D) r+x/3
E) 3(r+x)
sequence
This topic has expert replies
- GMATGuruNY
- 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
Let r=2 and x=3.datonman wrote:In the sequence, r, s, t, if each term after the first is x more than the previous term, what is the average of r, s, and t in terms of r and x?
A) r + x
B) r + x/3
C) r + 2x/3
D) r+x/3
E) 3(r+x)
Since each term is x=3 more than the previous term, we get:
r, s, t = 2, 5, 8.
Average of r, s and t = (2+5+8)/3 = 5. This is our target.
Now plug r=2 and x=3 into the answers to see which yields our target of 5.
Only A works:
r+x = 2+3 = 5.
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
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
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Another approach:datonman wrote:In the sequence, r, s, t, if each term after the first is x more than the previous term, what is the average of r, s, and t in terms of r and x?
A) r + x
B) r + x/3
C) r + 2x/3
D) r+x/3
E) 3(r+x)
There's a nice rule that says, "In a set where the numbers are equally spaced, the mean will equal the median."
Since each term is x greater than the term before it, these values are equally spaced.
So, the mean (average) = the median
Here, the median is s, so the average must be s
HOWEVER, the question wants the answer in terms of r and x.
We know that s is x greater than r
So, s = r + x
So, the mean = median = s = r + x
Answer: A
Cheers,
Brent
-
- Master | Next Rank: 500 Posts
- Posts: 447
- Joined: Fri Nov 08, 2013 7:25 am
- Thanked: 25 times
- Followed by:1 members
The 3 terms are: r, r+x, r + 2x
The total is 3r + 3x
So the mean average is (3r + 3x)/3 = r + x
Answer = A
The total is 3r + 3x
So the mean average is (3r + 3x)/3 = r + x
Answer = A