GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 26 May 2020, 05:45 ### GMAT Club Daily Prep

#### 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

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.  # If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30

Author Message
TAGS:

### Hide Tags

Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8990
GMAT 1: 760 Q51 V42
GPA: 3.82
If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags 00:00

Difficulty:   15% (low)

Question Stats: 74% (01:08) correct 26% (01:40) wrong based on 113 sessions

### HideShow timer Statistics

If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30, what is the smallest number?

A. 5
B. 10
C. 15
D. 20
E. 25

_________________
Intern  B
Joined: 13 Mar 2016
Posts: 25
Location: India
Concentration: General Management, Entrepreneurship
WE: General Management (Energy and Utilities)
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

1
5x, 5(x+1), 5(x+2), 5(x+3), 5(x+4) are 5 multiples
(50+25X)/5=30
X=4
5X ie smallest number = 20
Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8990
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

==> From 5n,5n+5, 5n+10, 5n+15, 5n+20, the average is 5n+10, and from 5n+10=30, you get 5n=20, n=4. The smallest number=5n=5(4)=20, hence the answer is D.

_________________
Target Test Prep Representative G
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2800
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

MathRevolution wrote:
If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30, what is the smallest number?

A. 5
B. 10
C. 15
D. 20
E. 25

We can denote the first multiple of 5 as x and the last multiple of 5 as x + 20. Since we have an evenly spaced set of integers, we can use the following average formula:

(least multiple of 5 in the set + greatest multiple of 5 in the set)/2 = average

(x + x + 20)/2 = 30

2x + 20 = 60

2x = 40

x = 20

Thus, the smallest number in the set is 20.

_________________

# Jeffrey Miller

Jeff@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Director  S
Status: Come! Fall in Love with Learning!
Joined: 05 Jan 2017
Posts: 514
Location: India
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

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
_________________
GMAT Mentors Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 8990
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

==> If the average of 5 consecutive multiples of 5 is 30, from 20,25,30,35,40, the smallest multiple of 5 becomes 20.

_________________
Manager  D
Joined: 17 May 2015
Posts: 237
If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

1
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  S
Status: active
Joined: 25 Jan 2016
Posts: 124
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

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
Board of Directors D
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4989
Location: India
GPA: 3.5
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

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  G
Joined: 09 Feb 2015
Posts: 321
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

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
Intern  B
Joined: 25 Mar 2017
Posts: 29
Location: India
GMAT 1: 650 Q49 V31
GMAT 2: 700 Q47 V39 GPA: 3.1
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

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

Sent from my ONEPLUS A3003 using GMAT Club Forum mobile app
Current Student D
Joined: 12 Aug 2015
Posts: 2522
Schools: Boston U '20 (M)
GRE 1: Q169 V154 Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

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.

_________________
Target Test Prep Representative V
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 10556
Location: United States (CA)
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

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

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Manager  B
Joined: 18 Dec 2017
Posts: 205
Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  [#permalink]

### Show Tags

1
Average is 30 and two consecutive multiple of 5 before 30 are 25 and 20.

Posted from my mobile device Re: If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30   [#permalink] 09 Apr 2020, 20:05

# If the average (arithmetic mean) of 5 consecutive multiples of 5 is 30  