Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.
Customized for You
we will pick new questions that match your level based on your Timer History
Track Your Progress
every week, we’ll send you an estimated GMAT score based on your performance
Practice Pays
we will pick new questions that match your level based on your Timer History
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:
The sequence \(a_1\), \(a_2\), \(a_3\), \(a_4\), \(a_5\) is such that \(a_n= a_{n-1} + 5\) for \(2\leq n \leq 5\). If \(a_5 = 31\), what is the value of \(a_1\) ?
(A) 1 (B) 6 (C) 11 (D) 16 (E) 21
Problem Solving Question: 67 Category:Algebra Sequences Page: 70 Difficulty: 600
Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.
We'll be glad if you participate in development of this project: 1. Please provide your solutions to the questions; 2. Please vote for the best solutions by pressing Kudos button; 3. Please vote for the questions themselves by pressing Kudos button; 4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.
The sequence a1, a2, a3, a4, a5 is such that an=a(n-1)+5 for
[#permalink]
Show Tags
30 Jan 2014, 01:50
1
SOLUTION
The sequence \(a_1\), \(a_2\), \(a_3\), \(a_4\), \(a_5\) is such that \(a_n= a_{n-1} + 5\) for \(2\leq n \leq 5\). If \(a_5 = 31\), what is the value of \(a_1\) ?
Re: The sequence a1, a2, a3, a4, a5 is such that an=a(n-1)+5 for
[#permalink]
Show Tags
30 Jan 2014, 03:10
1
1
The sequence \(a_1\), \(a_2\), \(a_3\), \(a_4\), \(a_5\) is such that \(a_n= a_{n-1} + 5\) for \(2\leq n \leq 5\). If \(a_5 = 31\), what is the value of \(a_1\) ?
(A) 1 (B) 6 (C) 11 (D) 16 (E) 21
Sol: Given a5=31....and also a5=a4+5 ---> a4=26-----> a3=21----->a2=16 ---->a1=11. Ans C
600 level is okay
_________________
“If you can't fly then run, if you can't run then walk, if you can't walk then crawl, but whatever you do you have to keep moving forward.”
Re: The sequence a1, a2, a3, a4, a5 is such that an=a(n-1)+5 for
[#permalink]
Show Tags
30 Jan 2014, 10:42
2
1
This answer can be easily be solve by A.P. The sequence is an A.P. with each term at an increment of 5 from the previous term. So a5 is nothing but a1+20.
Re: The sequence a1, a2, a3, a4, a5 is such that an=a(n-1)+5 for
[#permalink]
Show Tags
18 Mar 2014, 23:12
Bunuel wrote:
SOLUTION
The sequence \(a_1\), \(a_2\), \(a_3\), \(a_4\), \(a_5\) is such that \(a_n= a_{n-1} + 5\) for \(2\leq n \leq 5\). If \(a_5 = 31\), what is the value of \(a_1\) ?
Re: The sequence a1, a2, a3, a4, a5 is such that an=a(n-1)+5 for
[#permalink]
Show Tags
19 Mar 2014, 01:59
1
havoc7860 wrote:
Bunuel wrote:
SOLUTION
The sequence \(a_1\), \(a_2\), \(a_3\), \(a_4\), \(a_5\) is such that \(a_n= a_{n-1} + 5\) for \(2\leq n \leq 5\). If \(a_5 = 31\), what is the value of \(a_1\) ?
Re: The sequence a1, a2, a3, a4, a5 is such that an=a(n-1)+5 for
[#permalink]
Show Tags
26 Mar 2018, 17:34
Quote:
The sequence \(a_1\), \(a_2\), \(a_3\), \(a_4\), \(a_5\) is such that \(a_n= a_{n-1} + 5\) for \(2\leq n \leq 5\). If \(a_5 = 31\), what is the value of \(a_1\) ?
(A) 1 (B) 6 (C) 11 (D) 16 (E) 21
a(5) = 31, so:
a(5) = a(4) + 5
31 = a(4) + 5
26 = a(4)
The pattern is to subtract 5 to obtain the value of the previous term in this recursively-defined sequence.
Thus, a(3) = 21, a(2) =16, and a(1) = 11.
Answer: C
_________________
Jeffery Miller Head of GMAT Instruction
GMAT Quant Self-Study Course 500+ lessons 3000+ practice problems 800+ HD solutions
close
91% (01:18) correct 
