What is the value of t?

[jjjinapinch]

What is the value of t?

(1) s + t = 6 + s
(2) t^3 = 216

Official Guide question
Answer: D

[Brent@GMATPrepNow]

What is the value of t?
(1) s + t = 6 + s
(2) t^3 = 216

Official Guide question
Answer: D

Target question: What is the value of t?

Statement 1: s + t = 6 + s
Subtract s from both sides to get: t = 6...DONE!
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: t^3 = 216
Only one value satisfies this equation: t = 6...DONE!
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: D

Cheers,
Brent

[Jay@ManhattanReview]

What is the value of t?

(1) s + t = 6 + s
(2) t^3 = 216

Official Guide question
Answer: D

While the first statement is easy, let's discuss the second statement.

If the exponent of a number is an odd integer, you get a unique value of the number.

Let's take the following examples.

1. t^2 = 36; exponent 2 is even

= t^2 = 6^2; or t^2 = (-6)^2;

In this case t = 6 or -6. No unique value.

2. t^3 = 216; exponent 3 is odd

= t^3 = 6^3; or t^3 ≠ (-6)^3;

In this case t = 6. A unique value.

The correct answer: D

Hope this helps!

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide

-Jay
_________________
Manhattan Review GMAT Prep

Locations: New York | Singapore | Doha | Lausanne | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.

[[email protected]]

Hi jjjinapinch,

This prompt is built around a couple of standard Arithmetic rules. We're asked for the value of T.

1) S + T = 6 + S

If we subtract S from both sides of the equation, we get... T = 6
Fact 1 is SUFFICIENT.

2) T^3 = 216

While equations that involve exponents sometimes result in more than one solution, this equation has JUST one solution. Here's why:

(positive)^3 = positive
(negative)^3 = negative
(0)^3 = 0

Since T^3 = +216, there can be JUST ONE solution - one positive solution (and while T=6 is that solution, you don't have to technically calculate it to KNOW that there's just one solution). Thus....
Fact 2 is SUFFICIENT.

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

[Jeff@TargetTestPrep]

What is the value of t?

(1) s + t = 6 + s
(2) t^3 = 216

Official Guide question
Answer: D

We need to determine the value of t.

Statement One Alone:

s + t = 6 + s

We can subtract s from both sides of the equation and obtain:

t = 6

Statement one is sufficient to answer the question.

Statement Two Alone:

t^3 = 216

We can take the cube root of t^3 and 216 and we have:

t = 6

Statement two is sufficient to answer the question.

Answer: D

[AdityaBir]

1) s+t = 6+s
t=6.
statement 1) alone is sufficient.
2) t^3 = 216
t=6 (since exponent is odd so only one value will satisfy it)
statement 2) alone is also sufficient.
Option D is correct.