The figure above represents a rectangular garden bordered by a

the statement says the uniform width of the walkway is 3 feet. Nothing more info on that. Lets check the answer.

1. We know the outer perimeter as 124 ft. So we can find the length and width. And if we subtract the 3 feet(Uniform) from both length and breath we find the perimeter of the garden- Sufficient.

2. we know the area, but we do not know whether the area includes the walkway or not. . Also in either case, we may have multiple values of length and breath which can give the area of 600 feet. So In-sufficient


The answer is A.
_________________

Let x and y be two sides of the garden. So what is 2(x+y)?

St1) If outer perimeter of a walkaway is 124, 2*{(x+6)+(y+6)} = 124. We can calculate x+y from it. SUFF
St2) x*y=600. INSUFF

2*{(x+6)+(y+6)} = 124

{(x+6)+(y+6)} = 62

X+Y+12=62

X+Y=50

But its imp to realize we must resist doing these sorts of calculations on DS as its enough to know if we have sufficient information to answer the question

what does "outer perimeter" mean exactly though? they didn't give any info about garden just walkway so how is 1 sufficient?

Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.


The figure above represents a rectangular garden bordered by a walkaway that has a uniform width of 3 feet. What's the perimeter of the garden?

1) The outer perimeter of the walkaway is 124 feet
2) The area of the garden is 600 feet.

Modify the original condition and the question. Suppose the width and the length of the garden ‘a’ and ‘b’ respectively. Then you can come up with an equation 2(a+b)=?. In 1), you can get a+b=50 from 2(a+b)+24=124, which is sufficient and therefore the answer is A.


-> Once we modify the original condition and the question according to the variable approach method 1, we can solve approximately 30% of DS questions.

i understand St2) but am lost on St1).

Where do you get (x+6)(y+6)?

I understand Perimeter = 2(x+y). if outer perimeter is 124, isn't the equation: 124 = 2(x+y)? I understand the walkway (3') borders the garden so there needs to be a little more to the "x+y" but i can't understand why you put "x+6 and y"+6" here...

Bunuel - What do we mean here by outer perimeter?
If the garden is surrounded by a walkway and the perimeter of that is 124 feet, then ideally the perimeter should be calculated as the perimeter of the bigger box - Perimeter of the garden.

Which i tried to solve but the variables get cancelled out 2(X+6+y+6)<------Perimeter of bigger box MINUS 2(X+Y)<------ Perimeter of the Garden(Smaller box)=124

Please correct me.

The outer perimeter of the walkaway is the perimeter of the larger rectangle.
_________________

All lengths are considered in feet.

\(? = 2\left[ {\left( {a - 6} \right) + \left( {b - 6} \right)} \right]\,\,\,\,\,\,\,\,\,\, \Leftrightarrow \,\,\,\,\boxed{\,\,\,? = a + b\,\,}\)



\(\left( 1 \right)\,\,\,2\left( {a + b} \right) = 124\,\,\,\, \Rightarrow \,\,\,\,? = a + b\,\,\,{\text{unique}}\)

\(\left( 2 \right)\,\,\left( {a - 6} \right)\left( {b - 6} \right) = 600\,\,\,\,\left\{ \begin{gathered}\\
\,{\text{Take}}\,\,\left( {a,b} \right) = \left( {16,66} \right)\,\,\,\,\, \Rightarrow \,\,\,\,{\text{?}}\,\,{\text{ = }}\,\,{\text{16 + 66}}\,\, \hfill \\\\
\,{\text{Take}}\,\,\left( {a,b} \right) = \left( {26,36} \right)\,\,\,\,\, \Rightarrow \,\,\,\,{\text{?}}\,\,{\text{ = }}\,\,{\text{26 + 36}} \ne {\text{16 + 66}}\,\, \hfill \\ \\
\end{gathered} \right.\)


This solution follows the notations and rationale taught in the GMATH method.

Regards,
Fabio.
_________________

The figure above represents a rectangular garden bordered by a walkaway that has a uniform width of 3 feet. What's the perimeter of the garden?

(1) The outer perimeter of the walkaway is 124 feet
(2) The area of the garden is 600 feet.

Let the smaller reactangle be of dimension lxb. We need the value of 2(l+b). The outher rectangle is of the dimension l+6, b+6.

1. 2l + 2b + 24 = 124; l+b =100. Insufficient.
2. lb = 600. Insufficient.
Combining, we have two variables and two equations. Solvable.
Sufficient.
C.

A rectangular garden is bordered by a walkway that has uniform width of 3 feet. What is the perimeter?

Let \(x + 6 \)= walkway width
let \(y + 5\) = walkway length

What is \(x + y\)?

(1) If the outer perimeter is 124 feet, then

\(2(x+y+12) = 124\)
\(x+y+12 = 62\)
\(x+y = 50\)

SUFFICIENT

(2) We can't determine x or y from the area. INSUFFICIENT.

Answer is A.
_________________

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________