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

 It is currently 23 Oct 2018, 16:40

### 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

# The value of a precious stone is directly proportional to the cube of

Author Message
TAGS:

### Hide Tags

Senior PS Moderator
Joined: 26 Feb 2016
Posts: 3207
Location: India
GPA: 3.12
The value of a precious stone is directly proportional to the cube of  [#permalink]

### Show Tags

19 Nov 2017, 12:47
1
00:00

Difficulty:

45% (medium)

Question Stats:

66% (01:56) correct 34% (02:40) wrong based on 51 sessions

### HideShow timer Statistics

The value of a precious stone is directly proportional to the cube of its weight. If a big stone broke into three parts in the ratio 1:4:5, what was the percentage drop in the value of the stone?

A. 10%
B. 40%
C. 71%
D. 81%
E. 93%

source: Experts Global

_________________

You've got what it takes, but it will take everything you've got

PS Forum Moderator
Joined: 25 Feb 2013
Posts: 1216
Location: India
GPA: 3.82
The value of a precious stone is directly proportional to the cube of  [#permalink]

### Show Tags

19 Nov 2017, 13:24
3
1
pushpitkc wrote:
The value of a precious stone is directly proportional to the cube of its weight. If a big stone broke into three parts in the ratio 1:4:5, what was the percentage drop in the value of the stone?

A. 10%
B. 40%
C. 71%
D. 81%
E. 93%

source: Experts Global

Let the original weight of the stone be $$10$$ units

so original price $$P=10^3k=1000k$$, where $$k$$ is any constant

as the stone broke in the ratio $$1:4:5$$, so the weight of the three stones will be $$1$$, $$4$$ & $$5$$. Revised price will be

$$P_1=1^3k=k$$

$$P_2=4^3k=64k$$

$$P_3=5^3k=125K$$

So Total new price $$= k+64k+125k=190k$$

Hence reduction in price $$= 1000k-190k=810k$$

Reduction % $$= \frac{810k}{1000k}*100=81$$%

Option D
Intern
Joined: 16 Aug 2016
Posts: 15
Location: India
GMAT 1: 460 Q35 V19
GPA: 3.6
WE: Brand Management (Retail)
Re: The value of a precious stone is directly proportional to the cube of  [#permalink]

### Show Tags

19 Nov 2017, 13:48
Let's assume initial weight of the precious stone as 10 (1+4+5) and original value as 1000.
As the stone gets broken into 3 parts in the ratio of 1: 4: 5, therefore, the weights of the pieces will be in the same ratio.
Let the value of these 3 pieces be x, y, and z respectively, hence, we get that:
$$\frac{1000}{x}=\frac{10^3}{1^3}$$, or, x=1.
Similarly, $$\frac{1000}{y}=\frac{10^3}{4^3}$$, giving y=64, and
$$\frac{1000}{z}=\frac{10^3}{5^3}$$, giving z=125

Therefore, the new value of the stone will be x+y+z, or, 1+64+125 = 190.

%age change = $$\frac{Old Value - New Value}{Old Value}$$*100

%age change = $$\frac{1000-190}{1000}$$*100 = $$\frac{810}{1000}$$*100 = 81%
Re: The value of a precious stone is directly proportional to the cube of &nbs [#permalink] 19 Nov 2017, 13:48
Display posts from previous: Sort by