## By what percent was the price of a certain television set di

##### This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 367
Joined: 05 Jun 2015
Thanked: 3 times
Followed by:2 members

### By what percent was the price of a certain television set di

by NandishSS » Wed Mar 15, 2017 5:54 am

00:00

A

B

C

D

E

## Global Stats

By what percent was the price of a certain television set discounted for a sale?

(1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price.
(2) The price of the television set was discounted by $60 for the sale. Source: OG 16 OA:A ### GMAT/MBA Expert GMAT Instructor Posts: 2094 Joined: 04 Dec 2012 Thanked: 1443 times Followed by:245 members by ceilidh.erickson » Wed Mar 15, 2017 6:03 am ## Timer 00:00 ## Your Answer A B C D E ## Global Stats There are several strategies we could use here: algebra or testing numbers. I'll demonstrate the latter first: Target question: By what percent was the price of a certain television set discounted for a sale? (1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price. Test 1: Before discount:$125
Discounted: $100 Percent decrease: 20% Test 2: Before discount:$12,500 (crazy price for a tv, but who cares?)
Discounted: $10,000 Percent decrease: 20% If we get the same answer when we test numbers of different orders of magnitude, we can assume it is SUFFICIENT. (2) The price of the television set was discounted by$60 for the sale.
Test 1:
Before discount: $100 Discounted:$40
Percent decrease: 60%

Test 2:
Before discount: $10,000 Discounted:$9,940
Percent decrease: 0.6%

Two different answers ==> INSUFFICIENT.

The answer is A.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education

GMAT Instructor
Posts: 15532
Joined: 25 May 2010
Location: New York, NY
Thanked: 13060 times
Followed by:1897 members
GMAT Score:790
by GMATGuruNY » Wed Mar 15, 2017 6:03 am

00:00

A

B

C

D

E

## Global Stats

NandishSS wrote:By what percent was the price of a certain television set discounted for a sale?

(1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price.
(2) The price of the television set was discounted by $60 for the sale. Statement 1: Case 1: Discounted price =$4, original price = $4 + (25% of$4) = 4+1 = $5. Since the price decreases from$5 to $4 -- a discount of$1 -- the discount percentage = (discount)/(original price) * 100 = (1/5)(100) = 20%.

Case 2: Discounted price = $8, original price =$8 + (25% of $8) = 8+2 =$10.
Since the price decreases from $10 to$8 -- a discount of $2 -- the discount percentage = (discount)/(original price) * 100 = (2/10)(100) = 20%. Since the discount percentage is THE SAME in each case, SUFFICIENT. Statement 2: Since the original price is unknown, it is not possible to determine the discount percentage. INSUFFICIENT. The correct answer is A. Mitch Hunt Private Tutor for the GMAT and GRE [email protected] If you find one of my posts helpful, please take a moment to click on the "UPVOTE" icon. Available for tutoring in NYC and long-distance. For more information, please email me at [email protected]. Student Review #1 Student Review #2 Student Review #3 ### GMAT/MBA Expert GMAT Instructor Posts: 2094 Joined: 04 Dec 2012 Thanked: 1443 times Followed by:245 members by ceilidh.erickson » Wed Mar 15, 2017 6:11 am ## Timer 00:00 ## Your Answer A B C D E ## Global Stats To set this up algebraically, assign variables: x = old price before discount y = new price after discount If we want to know the PERCENT CHANGE from the old price to the new price, we can write that as: (x - y)/x = ? Simplify that by splitting the fraction: (x/x) - (y/x) = ? 1 - (y/x) = ? Since this is DS, we would have sufficient information to answer the question if we knew the value of the ratio y/x. Target question: y/x = ? (1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price. Translate: x = 1.25y (1/1.25) = y/x We have a value for the ratio y/x. SUFFICIENT. (2) The price of the television set was discounted by$60 for the sale.
Translate:
y = x - 60
We have a DIFFERENCE between the two variables, but we can't get a RATIO.
INSUFFICIENT.

The answer is A.

You may start to notice this trend in DS: when a question asks for a PROPORTION (percent, ratio, fraction) and no concrete values are given, another proportion is often sufficient (as in #1). A concrete value alone (as in #2) will not help to answer a proportion question, if not other values are given.
Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education

### GMAT/MBA Expert

GMAT Instructor
Posts: 2094
Joined: 04 Dec 2012
Thanked: 1443 times
Followed by:245 members
by ceilidh.erickson » Wed Mar 15, 2017 6:14 am

00:00

A

B

C

D

E

## Global Stats

Ceilidh Erickson
EdM in Mind, Brain, and Education
Harvard Graduate School of Education

### GMAT/MBA Expert

Elite Legendary Member
Posts: 10347
Joined: 23 Jun 2013
Location: Palo Alto, CA
Thanked: 2867 times
Followed by:508 members
GMAT Score:800
by [email protected] » Wed Apr 04, 2018 7:36 pm

00:00

A

B

C

D

E

## Global Stats

Hi All,

We're asked by what PERCENT was the price of a certain television set discounted for a sale. This question can be approached in a number of different ways; at it's heart though, the concept involves Percent Change (which is a relationship between two values).

1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price.

If the price of the television was 25% GREATER than the discounted price, then we can organize the the two prices in the following way:

Discounted Price = X
Regular Price = (1.25)(X)

Since the Regular Price is 'locked in' at 25% greater, we can use the Percentage Change Formula to calculate the Percent Decrease in price:

Percent Change = (New - Old)/(Old) = (X - 1.25X)/(1.25X) = (-.25X)/(1.25X) = -1/5 = -20% = a 20% decrease.
Fact 1 is SUFFICIENT

(2) The price of the television set was discounted by $60 for the sale. With the information in Fact 2, we don't know the Regular Price nor the Discounted Price. IF.... Regular Price =$60 and Discounted Price = $0, then the Percent Decrease is (60 - 0)/(60) = 60/60 = 1 = 100% discount Regular Price =$120 and Discounted Price = $60, then the Percent Decrease is (120 - 60)/(120) = 60/120 = 1/2 = 50% discount Fact 2 is INSUFFICIENT Final Answer: A GMAT assassins aren't born, they're made, Rich ### GMAT/MBA Expert GMAT Instructor Posts: 1460 Joined: 09 Apr 2015 Location: New York, NY Thanked: 39 times Followed by:20 members by [email protected] » Tue Apr 10, 2018 10:26 am ## Timer 00:00 ## Your Answer A B C D E ## Global Stats NandishSS wrote:By what percent was the price of a certain television set discounted for a sale? (1) The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price. (2) The price of the television set was discounted by$60 for the sale.
We need to determine the percent discount of the television.

Statement One Alone:

The price of the television set before it was discounted for the sale was 25 percent greater than the discounted price.

We can let n = the regular price and d = the discounted price:

1.25d = n

d = n/1.25

d = 100n/125 = n(100/125) = n(4/5)

So the television was discounted 20%.

Statement one alone is sufficient to answer the question.

Statement Two Alone:

The price of the television set was discounted by \$60 for the sale.

Since we do not know the regular price of the television, statement two alone is not sufficient to answer the question.

Answer: A

• Page 1 of 1