GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 06 Dec 2019, 12:00

### 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

# The sum of three numbers is 20. The first is four times the sum of the

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 59587
The sum of three numbers is 20. The first is four times the sum of the  [#permalink]

### Show Tags

19 Mar 2019, 02:28
00:00

Difficulty:

25% (medium)

Question Stats:

79% (02:22) correct 21% (03:08) wrong based on 34 sessions

### HideShow timer Statistics

The sum of three numbers is 20. The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

(A) 28
(B) 40
(C) 100
(D) 400
(E) 800

_________________
VP
Joined: 31 Oct 2013
Posts: 1489
Concentration: Accounting, Finance
GPA: 3.68
WE: Analyst (Accounting)
Re: The sum of three numbers is 20. The first is four times the sum of the  [#permalink]

### Show Tags

19 Mar 2019, 03:27
1
Bunuel wrote:
The sum of three numbers is 20. The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

(A) 28
(B) 40
(C) 100
(D) 400
(E) 800

3rd = x

2 nd = 7x

1 st = 4(x + 7x ) = 32x.

x + 7x + 32x = 20

x = 1/2.

we are looking for product = x*7x*32x = 1/2 * 7 * 1/2 * 32*1/2 = 1/2 * 1/2 * 1/2 * 32 * 7 = 28.

GMAT Club Legend
Joined: 18 Aug 2017
Posts: 5428
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: The sum of three numbers is 20. The first is four times the sum of the  [#permalink]

### Show Tags

19 Mar 2019, 06:37
Bunuel wrote:
The sum of three numbers is 20. The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

(A) 28
(B) 40
(C) 100
(D) 400
(E) 800

a+b+c=20
a=4*(b+c)
b=7c
so
4b+4c+7c+c=20
40c=20
c=1/2
b= 7/2
a= 16
so a*b*c = 16*7/4 = 28
IMO A
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 8620
Location: United States (CA)
Re: The sum of three numbers is 20. The first is four times the sum of the  [#permalink]

### Show Tags

21 Mar 2019, 17:52
Bunuel wrote:
The sum of three numbers is 20. The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

(A) 28
(B) 40
(C) 100
(D) 400
(E) 800

We can let the numbers be a, b, and c; thus:

a + b + c = 20

and

a = 4(b + c)

a = 4b + 4c

and

b = 7c

Substituting, we have:

a = 4(7c) + 4c

a = 32c

Substituting again, we have:

32c + 7c + c = 20

40c = 20

c = 1/2, so b = 7/2, and a = 4(7/2 + 1/2) = 4(4) = 16.

The product of all 3 numbers is:

16 x 7/2 x 1/2 = 16 x 7/4 = 28.

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

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.

CR Forum Moderator
Joined: 25 Apr 2018
Posts: 671
GMAT 1: 680 Q49 V34
The sum of three numbers is 20. The first is four times the sum of the  [#permalink]

### Show Tags

24 Mar 2019, 07:16
Bunuel wrote:
The sum of three numbers is 20. The first is four times the sum of the other two. The second is seven times the third. What is the product of all three?

(A) 28
(B) 40
(C) 100
(D) 400
(E) 800

Given
a+b+c=20
a=4*(b+c)
b=7c

=> 40c=20
=> c=1/2 and b= 7/2
=> a= 16

a*b*c = 16*1/2*7/2
=> 28

Option A is the correct choice
The sum of three numbers is 20. The first is four times the sum of the   [#permalink] 24 Mar 2019, 07:16
Display posts from previous: Sort by