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

 It is currently 17 Oct 2018, 09:20

# Q&A in Progress!

### 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

# During a two-year period, the water level in a lake decreased by 20 pe

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 49968
During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

10 May 2017, 02:37
00:00

Difficulty:

5% (low)

Question Stats:

96% (01:09) correct 4% (03:03) wrong based on 46 sessions

### HideShow timer Statistics

During a two-year period, the water level in a lake decreased by 20 percent by the end of the first year and increased by 10 percent by the end of the second year. If the lake began the period with a water level of w feet, what was the level, in feet, by the end of the period?

A. 1.2w
B. 1.1w
C. 0.9w
D. 0.88w
E. 0.8w

_________________
Intern
Joined: 12 Nov 2016
Posts: 16
Re: During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

10 May 2017, 03:06
Initial level = w
After the 1st year, water level reduces by 20%. Hence, the resulting water level would be 0.8w
After the 2nd year, the water level increased by 10%. Hence, the resultant water level would be 1.1*0.8w= 0.88w
Hence, Option D should be the correct answer.
Senior SC Moderator
Joined: 22 May 2016
Posts: 2033
During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

10 May 2017, 08:45
Bunuel wrote:
During a two-year period, the water level in a lake decreased by 20 percent by the end of the first year and increased by 10 percent by the end of the second year. If the lake began the period with a water level of w feet, what was the level, in feet, by the end of the period?

A. 1.2w
B. 1.1w
C. 0.9w
D. 0.88w
E. 0.8w

Decrease by 20% [1-.20] = .80
Increase by 10% = [1+.10] 1.10

(.8)(1.1) = .88

Multiply that product by original value, w ==> .88w

_________________

The only thing more dangerous than ignorance is arrogance.
-- Albert Einstein

Target Test Prep Representative
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2830
Re: During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

12 May 2017, 13:40
Bunuel wrote:
During a two-year period, the water level in a lake decreased by 20 percent by the end of the first year and increased by 10 percent by the end of the second year. If the lake began the period with a water level of w feet, what was the level, in feet, by the end of the period?

A. 1.2w
B. 1.1w
C. 0.9w
D. 0.88w
E. 0.8w

We are given that the lake began at a level of w feet and that the level decreased 20% and then increased 10%. So the ending level is:

w x 0.8 x 1.1 = 0.88w

_________________

Jeffery Miller

GMAT Quant Self-Study Course
500+ lessons 3000+ practice problems 800+ HD solutions

Director
Joined: 04 Dec 2015
Posts: 701
Location: India
Concentration: Technology, Strategy
Schools: ISB '19, IIMA , IIMB, XLRI
WE: Information Technology (Consulting)
Re: During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

16 May 2017, 05:42
During a two-year period, the water level in a lake decreased by 20 percent by the end of the first year and increased by 10 percent by the end of the second year. If the lake began the period with a water level of w feet, what was the level, in feet, by the end of the period?

A. 1.2w
B. 1.1w
C. 0.9w
D. 0.88w
E. 0.8w

Water level = w
After first year water level decreased by 20% = 80% of w
After second year water level increased by 10% = 110% of 80% of w
Therefore water level by the end of period = $$\frac{110}{100}$$ x $$\frac{80}{100}$$ x w = $$\frac{88}{100}$$ x w = 0.88w

_________________
Kindly press "+1 Kudos" to appreciate
Board of Directors
Status: QA & VA Forum Moderator
Joined: 11 Jun 2011
Posts: 4094
Location: India
GPA: 3.5
Re: During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

16 May 2017, 08:32
Bunuel wrote:
During a two-year period, the water level in a lake decreased by 20 percent by the end of the first year and increased by 10 percent by the end of the second year. If the lake began the period with a water level of w feet, what was the level, in feet, by the end of the period?

A. 1.2w
B. 1.1w
C. 0.9w
D. 0.88w
E. 0.8w

Let, initial water level be "w"

Water level after 1st year = $$80/100*w$$ $$= 0.80w$$
Water level after 2nd year = $$\frac{0.80w*110}{100}$$ $$= 0.88w$$

Thus, level of water in feet after 2nd year is 0.88w
_________________

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 )

Director
Joined: 13 Mar 2017
Posts: 622
Location: India
Concentration: General Management, Entrepreneurship
GPA: 3.8
WE: Engineering (Energy and Utilities)
Re: During a two-year period, the water level in a lake decreased by 20 pe  [#permalink]

### Show Tags

16 May 2017, 08:37
Bunuel wrote:
During a two-year period, the water level in a lake decreased by 20 percent by the end of the first year and increased by 10 percent by the end of the second year. If the lake began the period with a water level of w feet, what was the level, in feet, by the end of the period?

A. 1.2w
B. 1.1w
C. 0.9w
D. 0.88w
E. 0.8w

Initial water level = w feet.
at the end of first year = 0.8 w
at the end of 2nd year = 0.8 x 1.1 w = 0.88 w

_________________

CAT 2017 99th percentiler : VA 97.27 | DI-LR 96.84 | QA 98.04 | OA 98.95
UPSC Aspirants : Get my app UPSC Important News Reader from Play store.

MBA Social Network : WebMaggu

Appreciate by Clicking +1 Kudos ( Lets be more generous friends.)

What I believe is : "Nothing is Impossible, Even Impossible says I'm Possible" : "Stay Hungry, Stay Foolish".

Re: During a two-year period, the water level in a lake decreased by 20 pe &nbs [#permalink] 16 May 2017, 08:37
Display posts from previous: Sort by