Quantitative question - please help!

[speechfan222]

I'm curious about a quantitative question that I was asked on a practice GRE test.

A, B, and C are the lengths of the sides of the triangle. Quantity A is 2b and Quantity B is a+b+c.

When drawing a picture for this question, how do I know which triangle to use and which side is a, b, or c? I know I can substitute any number in for the variable to determine whether value A or B is greater, but I'm not sure how to draw the triangle.

Please help!

[Vince Kotchian GRE Prep]

I will give you a hint (since it will increase your skill more than if I just explain the whole question): this question is testing the "3rd side rule of triangles". I.e., any two sides of a triangle must add up to MORE than its remaining side. This has to be true of a triangle no matter which two sides you pick.

Another little hint: don't stress about how you draw the triangle.

FYI: this is a tough question!

[greMS15]

2 hours ago, speechfan222 said:

I'm curious about a quantitative question that I was asked on a practice GRE test.

A, B, and C are the lengths of the sides of the triangle. Quantity A is 2b and Quantity B is a+b+c.

When drawing a picture for this question, how do I know which triangle to use and which side is a, b, or c? I know I can substitute any number in for the variable to determine whether value A or B is greater, but I'm not sure how to draw the triangle.

Please help!

is the  answer B?

[Brent@GreenlightGRE]

IMPORTANT RULE: If two sides of a triangle have lengths A and B, then:  the third side < A+B

So, for this particular question, we know that b < a + c

We have:

Quantity A: 2b

Quantity B: a + b + c 

Let's subtract b from both quantities to get: 

Quantity A: b

Quantity B: a + c

Aha! Our rule tells us that b < a + c, so it MUST be the case that Quantity B is greater. 
Answer: B

Cheers,

Brent - Greenlight Test Prep