Author 
Message 
TAGS:

Hide Tags

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 4707
GPA: 3.82

If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
20 Mar 2017, 02:43
Question Stats:
74% (00:51) correct 26% (01:16) wrong based on 87 sessions
HideShow timer Statistics
If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30, what is the smallest number of them? A. 5 B. 10 C. 15 D. 20 E. 25
Official Answer and Stats are available only to registered users. Register/ Login.
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The oneandonly World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. Find a 10% off coupon code for GMAT Club members. “Receive 5 Math Questions & Solutions Daily” Unlimited Access to over 120 free video lessons  try it yourself See our Youtube demo



Senior Manager
Joined: 05 Jan 2017
Posts: 435
Location: India

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
20 Mar 2017, 03:21
let the number be a , a+5, a+10, a+15, a+20 a +a +5 +a +10 +a+15+a+20 = 30*5 or 5a + 50 = 150 or a = 20
therefore the smallest number is 20



Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 4707
GPA: 3.82

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
22 Mar 2017, 01:49
==> If the average of 5 consecutive multiples of 5 is 30, from 20,25,30,35,40, the smallest multiple of 5 becomes 20. Therefore, the answer is D. Answer: D
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The oneandonly World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. Find a 10% off coupon code for GMAT Club members. “Receive 5 Math Questions & Solutions Daily” Unlimited Access to over 120 free video lessons  try it yourself See our Youtube demo



Manager
Joined: 17 May 2015
Posts: 210

If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
22 Mar 2017, 04:56
1
This post received KUDOS
MathRevolution wrote: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30, what is the smallest number of them? A. 5 B. 10 C. 15 D. 20 E. 25 Concept: For Arithmetic progression (or equally spaced series) arithmetic mean = median. => Median = 30 (3rd term of the series). Smallest number or 1st element will be 20. Answer D. Thanks.



Manager
Status: active
Joined: 25 Jan 2016
Posts: 170
Location: India
Concentration: Finance, Entrepreneurship
GPA: 4
WE: Web Development (Computer Software)

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
22 Mar 2017, 06:08
let the number be x,x+5,x+10,x+15,x+20 avg is 30
so 30*5=5x+50 5x=100 x=20 answer is D



Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 3258
Location: India
GPA: 3.5
WE: Business Development (Commercial Banking)

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
22 Mar 2017, 10:32
MathRevolution wrote: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30, what is the smallest number of them? A. 5 B. 10 C. 15 D. 20 E. 25 \(5a + 5b + 5c + 5d + 5e = 150\) Now, If the smallest number is 20 then we have.... \(20 + 25 + 30 + 35 + 40 = 150\) Thus, answer must be (D) 20
_________________
Thanks and Regards
Abhishek....
PLEASE FOLLOW THE RULES FOR POSTING IN QA AND VA FORUM AND USE SEARCH FUNCTION BEFORE POSTING NEW QUESTIONS
How to use Search Function in GMAT Club  Rules for Posting in QA forum  Writing Mathematical Formulas Rules for Posting in VA forum  Request Expert's Reply ( VA Forum Only )



Senior Manager
Joined: 09 Feb 2015
Posts: 382
Location: India
Concentration: Social Entrepreneurship, General Management
GMAT 1: 690 Q49 V34 GMAT 2: 720 Q49 V39
GPA: 2.8

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
28 Mar 2017, 04:27
Since the 5 numbers are consecutive multiples of 5 and the mean is 30 ,the middle number must be 30 so 20,25,30,35,40 Answer : D



Intern
Joined: 25 Mar 2017
Posts: 10

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
28 Mar 2017, 04:53
Let the numbers be n,n+5,n+10,n+15,n+20 ( because numbers are consecutive multiple of 5) Then (5n+50)/5=30 according to the question Solving which we get n=20 Answer D Sent from my ONEPLUS A3003 using GMAT Club Forum mobile app



Retired Moderator
Joined: 12 Aug 2015
Posts: 2341
GRE 1: 323 Q169 V154

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
08 Aug 2017, 01:46
For any A.P series => Mean = Median
Hence as number of terms = 5 Median => 3rd term.
Hence the series would be ==>
  30  
filling up the blanks => 20,25,30,35,40
Hence smallest => 20
Hence D.
_________________
Give me a hell yeah ...!!!!!



Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 2069
Location: United States (CA)

Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30 [#permalink]
Show Tags
10 Aug 2017, 09:52
MathRevolution wrote: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30, what is the smallest number of them? A. 5 B. 10 C. 15 D. 20 E. 25 Let’s let x = the smallest multiple of 5. The next consecutive multiple of 5 is (x + 5); the one after that will be (x + 10), and so on. We can create the following equation: x + x + 5 + x + 10 + x + 15 + x + 20 = 150 5x = 100 x = 20 Answer: D
_________________
Scott WoodburyStewart
Founder and CEO
GMAT Quant SelfStudy Course
500+ lessons 3000+ practice problems 800+ HD solutions




Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30
[#permalink]
10 Aug 2017, 09:52






