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

 It is currently 18 Jun 2019, 00:19 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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.  If the area of triangular region RST is 25, what is the

Author Message
TAGS:

Hide Tags

Math Revolution GMAT Instructor V
Joined: 16 Aug 2015
Posts: 7462
GMAT 1: 760 Q51 V42 GPA: 3.82
Re: If the area of triangular region RST is 25, what is the  [#permalink]

Show Tags

prasannar wrote:
If the area of triangular region RST is 25, what is the perimeter of RST?

(1) The length of one side of RST is $$5\sqrt{2}$$.
(2) RST is a right isosceles triangle.

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Assume b is the base and h is the height of the triangle.
(1/2)bh = 25.
Since we have 2 variables and 1 equation, D is most likely to be the answer. So, we should consider each of the conditions on their own first.

Condition 1)
Since there two cases, we can't determine the perimeter of RST.
We don't know which side is 5√2.
Those cases are b is 5√2 or another side length is 5√2.
This is not sufficient.

Condition 2)
Assume that the length of two legs is a.
The area of the right isosceles triangle is (1/2)a^2 = 25.
Then a = 5 and the hypotenuse is 5√2 .
The perimeter is 10 + 5√2.
Condition 2) is sufficient.

If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.
_________________
Retired Moderator V
Joined: 27 Oct 2017
Posts: 1225
Location: India
GPA: 3.64
WE: Business Development (Energy and Utilities)
Re: If the area of triangular region RST is 25, what is the  [#permalink]

Show Tags

Project DS Butler: Day 54: Data Sufficiency (DS107)

Bumping for DS project
_________________
Intern  B
Joined: 26 Jun 2018
Posts: 5
Location: India
Re: If the area of triangular region RST is 25, what is the  [#permalink]

Show Tags

Given, area of any triangle.
To find : its perimeter
So we need measurements of its sides somehow

S1: one side is given. It can be any side and further, no info about the type of triangle is given to help us find the other sides. So, NOT SUFFICIENT>

S2: type of triangle given . Combine this with area of the triangle. Base = height, and 0.5*base*height = 25
base = height = 5 root 2
thus, hypothenuse can also be determined using pythagoras theorem.
hence, the perimeter of the triangle can be determined.
so, S2 is SUFFICIENT Re: If the area of triangular region RST is 25, what is the   [#permalink] 02 Jan 2019, 12:19

Go to page   Previous    1   2   [ 23 posts ]

Display posts from previous: Sort by

If the area of triangular region RST is 25, what is the  