NEW HERE? LEARN MORE
closeclose
Last visit was: 25 Apr 2024, 15:22 It is currently 25 Apr 2024, 15:22
Decision Tracker
My Rewards
New posts
New comers' posts

Close
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
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel

If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arit

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92915
Own Kudos [?]: 619017 [3]
Given Kudos: 81595
Send PM
CAT Tests Forum Quiz Mode
If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arit [#permalink] New post   02 Jan 2018, 01:31
3
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

35% (medium)

Question Stats:

76% (02:34) correct 24% (03:08) wrong based on 173 sessions
Hide Show timer Statistics
If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arithmetic mean) of a, b, and c?

A. 3
B. 4
C. 5
D. 6
E. 7
ShowHide Answer
Official Answer
C
User avatar
L
AkshdeepS
VP
VP
Joined: 13 Apr 2013
Status:It's near - I can see.
Posts: 1479
Own Kudos [?]: 1603 [2]
Given Kudos: 1002
Location: India
Concentration: International Business, Operations
GPA: 3.01
WE:Engineering (Real Estate)
Send PM
Reviews Badge
Re: If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arit [#permalink] New post   02 Jan 2018, 04:51
2
Kudos
Bunuel wrote:
If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arithmetic mean) of a, b, and c?

A. 3
B. 4
C. 5
D. 6
E. 7


a + 2c = 8 ----> a = 8 - 2c ----->(I)
b + 5c = 13 -----> b = 13 - 5c ------> (II)

Use the values of a & b in 3a + 4b = 50

3 (8 - 2c) + 4 (13 - 5c) = 50

24 - 6c + 52 - 20c = 50

-26c = 50 - 76

c = 1

We can calculate b = 8 & a = 6

Average = \(\frac{(6 + 8 + 1)}{3}\) = 5

(C)
avatar
G
abannore
Current Student
Joined: 10 Jun 2018
Posts: 49
Own Kudos [?]: 85 [0]
Given Kudos: 36
Location: India
Schools: Kenan-Flagler '24 (WL) Jones (A)
GMAT 1: 690 Q49 V34
Send PM
Re: If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arit [#permalink] New post   04 Jan 2019, 21:46
Answer C

1. a+2c=8
2. b+5c=13
3. 3a+4b=50

Multiply equation 1. by 5 and equation 2. by 2 to cancel out c. After multiplying, equation 1. becomes 5a+10c=40
and equation 2. becomes 2b+10c=26
Subtracting these 2 equations: 5a-2b=14 .........(equation A)
Now we have 2 equations to solve:
A) 5a-2b=14
3. 3a+4b=50

Multiply equation A by 2 to equalize b and then add the two equations to give the value of a. Substitute the value of a in earlier equations to find value of b and c. The values are:
a= 6, b=8, c=1

Mean = (a+b+c)/3 = 15/3= 5
avatar
S
vipulshahi
Manager
Manager
Joined: 24 Sep 2013
Posts: 164
Own Kudos [?]: 109 [0]
Given Kudos: 40
Location: Saudi Arabia
GPA: 3.8
WE:Project Management (Energy and Utilities)
Send PM
Re: If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arit [#permalink] New post   03 Jun 2020, 22:53
a+2c = 8
b+5c = 13
3a + 4b = 50
Inserting each equation in one another

3a + 4(13-5c) = 50
3a + 52 - 20c = 50
3a-20c = -2
3(8-2c) - 20c = -2
24 - 6c - 20c = -2
26 = 26c
c=1
a= 6
b = 8

Mean = 15/3 = 5

IMO(C)
GMAT Club Bot
gmatclubot
Re: If a + 2c = 8, b + 5c = 13, and 3a + 4b= 50, what is the average (arit [#permalink]
03 Jun 2020, 22:53
Moderators:
Bunuel
Math Expert
92915 posts
yashikaaggarwal
Senior Moderator - Masters Forum
3137 posts

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne
Main navigation
GMAT Resources
Partners
MBA Resources
www.gmac.com|www.mba.com | | GMAT Club Rules | Terms and Conditions