NEW HERE? LEARN MORE
closeclose
Last visit was: 24 Apr 2024, 19:21 It is currently 24 Apr 2024, 19:21
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

A's present age in years is 40% of B's age. In X years, A's age will

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
L
Bunuel
Math Expert
Joined: 02 Sep 2009
Posts: 92900
Own Kudos [?]: 618824 [2]
Given Kudos: 81588
Send PM
CAT Tests Forum Quiz Mode
A's present age in years is 40% of B's age. In X years, A's age will [#permalink] New post   02 Apr 2020, 09:18
2
Bookmarks
Expert Reply
00:00
A
B
C
D
E

Difficulty:

45% (medium)

Question Stats:

68% (02:09) correct 32% (02:21) wrong based on 22 sessions
Hide Show timer Statistics
A's present age in years is 40% of B's age. In X years, A's age will be half of B's age. By what percentage will B's age increase during these X years?

A. 5
B. 10
C. 15
D. 20
E. 25
ShowHide Answer
Official Answer
D
User avatar
B
TheMongoose
Intern
Intern
Joined: 21 Sep 2012
Posts: 8
Own Kudos [?]: 4 [0]
Given Kudos: 111
Location: United States
Concentration: Operations, General Management
GPA: 3.5
Send PM
Re: A's present age in years is 40% of B's age. In X years, A's age will [#permalink] New post   02 Apr 2020, 09:36
A = 0.4B - (1)
A+x = (B+x)/2 - (2)
Put (1) in (2)
0.8B +2x = B + x
x = 0.2B
so in X years the increase is 0.2B i.e. 20%.

Bunuel wrote:
A's present age in years is 40% of B's age. In X years, A's age will be half of B's age. By what percentage will B's age increase during these X years?

A. 5
B. 10
C. 15
D. 20
E. 25
User avatar
L
CareerGeek
VP
VP
Joined: 20 Jul 2017
Posts: 1300
Own Kudos [?]: 3450 [0]
Given Kudos: 162
Location: India
Concentration: Entrepreneurship, Marketing
GMAT 1: 690 Q51 V30
WE:Education (Education)
Send PM
A's present age in years is 40% of B's age. In X years, A's age will [#permalink] New post   Updated on: 02 Apr 2020, 09:41
[quote="Bunuel"]A's present age in years is 40% of B's age. In X years, A's age will be half of B's age. By what percentage will B's age increase during these X years?

A. 5
B. 10
C. 15
D. 20
E. 25[/quote]


— A ———— B ———
— 0.4a ——— a ——— Present
— 0.4a+x —— a+x —— After x years

In X years, A's age will be half of B's age
—> 0.4a + x = 1/2(a + x)
—> 0.8a + 2x = a + x
—> x = 0.2a

% increase of B’s age = (x + a - a)/a*100
= x/a*100
= 0.2*100 = 20

Option D

[size=80][b][i]Posted from my mobile device[/i][/b][/size]

Originally posted by CareerGeek on 02 Apr 2020, 09:40.
Last edited by CareerGeek on 02 Apr 2020, 09:41, edited 1 time in total.
User avatar
G
preetamsaha
Senior Manager
Senior Manager
Joined: 14 Oct 2019
Status:Today a Reader; Tomorrow a Leader.
Posts: 346
Own Kudos [?]: 344 [0]
Given Kudos: 127
Location: India
GPA: 4
WE:Engineering (Energy and Utilities)
Send PM
Re: A's present age in years is 40% of B's age. In X years, A's age will [#permalink] New post   02 Apr 2020, 09:40
let, at present B's age is a
so, A's age is 0.4a
in X years , A's age will be half of B's age
so, a+x = 2*(0.4+x)
or, a=0.2x

in x years, B's age increase x
so, percentage of increase = (x/a)*100 = 0.2*100 = 20

correct answer is D
GMAT Club Bot
gmatclubot
Re: A's present age in years is 40% of B's age. In X years, A's age will [#permalink]
02 Apr 2020, 09:40
Moderators:
Bunuel
Math Expert
92900 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