NEW HERE? LEARN MORE
closeclose
Last visit was: 28 Apr 2024, 02:59 It is currently 28 Apr 2024, 02:59
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

Charu invested Rs.12000 at 10% simple interest. After 2.5 years

SORT BY:
Date
Kudos
Tags:
Find Similar Topics 
Show Tags
Hide Tags
User avatar
D
Suraj0184
Senior Manager
Senior Manager
Joined: 03 Jun 2022
Posts: 408
Own Kudos [?]: 375 [5]
Given Kudos: 9
Location: India
Send PM
Charu invested Rs.12000 at 10% simple interest. After 2.5 years [#permalink] New post   12 Sep 2022, 09:36
4
Bookmarks
00:00
A
B
C
D
E

Difficulty:

45% (medium)

Question Stats:

64% (02:21) correct 36% (02:49) wrong based on 39 sessions
Hide Show timer Statistics
Charu invested Rs.12000 at 10% simple interest. After 2.5 years Seema also invested Rs. 10000 at 16% rate of interest (simple interest). In how many years after Seema’s investment, their amounts (Principal + Interest) become equal?

A. 10
B. 10.5
C. 12,5
D. 15
C. 18
ShowHide Answer
Official Answer
C
User avatar
G
SaquibHGMATWhiz
GMATWhiz Representative
Joined: 23 May 2022
Posts: 640
Own Kudos [?]: 430 [0]
Given Kudos: 6
Location: India
GMAT 1: 760 Q51 V40
Send PM
Re: Charu invested Rs.12000 at 10% simple interest. After 2.5 years [#permalink] New post   12 Sep 2022, 23:30
Expert Reply
Suraj0184 wrote:
Charu invested Rs.12000 at 10% simple interest. After 2.5 years Seema also invested Rs. 10000 at 16% rate of interest (simple interest). In how many years after Seema’s investment, their amounts (Principal + Interest) become equal?

A. 10
B. 10.5
C. 12,5
D. 15
C. 18

Solution:

Let us assume that \(n\) years after Seema's investment the amount of Charu and Seems becomes equal.

Charu's amount \(n\) years after Seema's investment \(=12000+\frac{12000\times 10\times (n+2.5)}{100}=12000+1200(n+2.5)\)
Seems's amount \(n\) years after Seema's investment \(=10000+\frac{10000\times 16\times n}{100}=10000+1600n\)

According to the question, \(12000+1200(n+2.5)=10000+1600n\)
\(⇒12000+1200n+3000=10000+1600n\)
\(⇒1200n-1600n=10000-12000-3000\)
\(⇒-400n=-5000\)
\(⇒400n=5000\)
\(⇒n=\frac{5000}{400}\)
\(⇒n=12.5\)

Hence the right answer is Option C
User avatar
L
KarishmaB
Tutor
Joined: 16 Oct 2010
Posts: 14835
Own Kudos [?]: 64963 [2]
Given Kudos: 428
Location: Pune, India
Send PM
Re: Charu invested Rs.12000 at 10% simple interest. After 2.5 years [#permalink] New post   12 Sep 2022, 23:50
1
Kudos
1
Bookmarks
Expert Reply
Suraj0184 wrote:
Charu invested Rs.12000 at 10% simple interest. After 2.5 years Seema also invested Rs. 10000 at 16% rate of interest (simple interest). In how many years after Seema’s investment, their amounts (Principal + Interest) become equal?

A. 10
B. 10.5
C. 12,5
D. 15
C. 18


This is similar to a relative speed question.

Charu earns 1200 in interest every year so in the first 2.5 years, she earns Rs. 3000. So at the end of 2.5 years,
Charu's total is 2000 (she invests 2000 more than Seema) + 3000 = 5000 extra.

Seema earns 1600 in interest every year. So she earns Rs 400 more than Charu then on and must make up the 5000 difference between them.

Time taken by Seema to make up this difference = 5000/400 = 12.5 years

Answer (C)
User avatar
southpaw21
Intern
Intern
Joined: 10 Oct 2021
Posts: 1
Own Kudos [?]: 0 [0]
Given Kudos: 6
Send PM
Charu invested Rs.12000 at 10% simple interest. After 2.5 years [#permalink] New post   09 Oct 2022, 07:29
KarishmaB wrote:
Suraj0184 wrote:
Charu invested Rs.12000 at 10% simple interest. After 2.5 years Seema also invested Rs. 10000 at 16% rate of interest (simple interest). In how many years after Seema’s investment, their amounts (Principal + Interest) become equal?

A. 10
B. 10.5
C. 12,5
D. 15
C. 18


This is similar to a relative speed question.

Charu earns 1200 in interest every year so in the first 2.5 years, she earns Rs. 3000. So at the end of 2.5 years,
Charu's total is 2000 (she invests 2000 more than Seema) + 3000 = 5000 extra.

Seema earns 1600 in interest every year. So she earns Rs 400 more than Charu then on and must make up the 5000 difference between them.

Time taken by Seema to make up this difference = 5000/400 = 12.5 years

Answer (C)


karishma, I like your approach. Can you help in finding mistake in my solution please?

Charu invested 2.5 years before Seema and given her 10% interest, she would've made 3000 interest on her amount in that time. This makes her investment to be 12000 + 3000 = 15000.

Now, Charu has 15000 amount to invest while Seema starts off with 10000.

Total amount with Charu should equal to Seema's in 't' years

Hence,
15000 * [1 + 10/100*t] = 10000 * [1+ 16/100*t]

Solving above gives me t=50 which obviously is wrong.
GMAT Club Bot
gmatclubot
Charu invested Rs.12000 at 10% simple interest. After 2.5 years [#permalink]
09 Oct 2022, 07:29
Moderators:
Bunuel
Math Expert
92964 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