What the value of w^-2?
(1) w^-1 = 1/2
(2) w^3 = 8
Official Guide question
Answer: D
What the value of w^-2?
This topic has expert replies
-
- Senior | Next Rank: 100 Posts
- Posts: 83
- Joined: Mon Jul 24, 2017 8:16 am
- Followed by:1 members
GMAT/MBA Expert
- Brent@GMATPrepNow
- GMAT Instructor
- Posts: 16207
- Joined: Mon Dec 08, 2008 6:26 pm
- Location: Vancouver, BC
- Thanked: 5254 times
- Followed by:1268 members
- GMAT Score:770
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Target question: What is the value of w^-2?jjjinapinch wrote:What the value of w^-2?
(1) w^-1 = 1/2
(2) w^3 = 8
Official Guide question
Answer: D
Statement 1: w^(-1) = 1/2
w^(-1) = 1/w
So, statement 1 is telling us that 1/w = 1/2, which means w = 2, which means w^(-2) = 2^(-2) = 1/4
Since we can answer the target question with certainty, statement 1 is SUFFICIENT
Statement 2: w^3 = 8
Only one value of w satisfies this equation: w = 2, which means w^(-2) = 2^(-2) = 1/4
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent
GMAT/MBA Expert
- [email protected]
- Elite Legendary Member
- Posts: 10392
- Joined: Sun Jun 23, 2013 6:38 pm
- Location: Palo Alto, CA
- Thanked: 2867 times
- Followed by:511 members
- GMAT Score:800
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
Hi All,
We're asked for the value of w^(-2). This is a great example of a 'concept question' - meaning that you don't actually have to do any math to get the answer as long as you understand the concept(s) involved.
The concepts tested here are all about exponents of numbers. The two FACTS both deal with ODD exponents. When an exponent is an ODD number, there is just one solution and the 'sign' will match whatever the 'sign' of the number is. For example:
A^1 = 2 has just one solution: +2
X^3 = -27 has just one solution: -3
Y^(-1) = 1/4 has just one solution: +4
Z^(-3) = 1/125 has just one solution: +5
Etc.
1) W^-1 = 1/2
The equation in Fact 1 has an ODD exponent, so there is just one solution. Since W has just one value, there would be just one value of W^(-2).
Fact 1 is SUFFICIENT.
2) W^3 = 8
The equation in Fact 2 has an ODD exponent, so there is just one solution. Since W has just one value, there would be just one value of W^(-2).
Fact 2 is SUFFICIENT.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
We're asked for the value of w^(-2). This is a great example of a 'concept question' - meaning that you don't actually have to do any math to get the answer as long as you understand the concept(s) involved.
The concepts tested here are all about exponents of numbers. The two FACTS both deal with ODD exponents. When an exponent is an ODD number, there is just one solution and the 'sign' will match whatever the 'sign' of the number is. For example:
A^1 = 2 has just one solution: +2
X^3 = -27 has just one solution: -3
Y^(-1) = 1/4 has just one solution: +4
Z^(-3) = 1/125 has just one solution: +5
Etc.
1) W^-1 = 1/2
The equation in Fact 1 has an ODD exponent, so there is just one solution. Since W has just one value, there would be just one value of W^(-2).
Fact 1 is SUFFICIENT.
2) W^3 = 8
The equation in Fact 2 has an ODD exponent, so there is just one solution. Since W has just one value, there would be just one value of W^(-2).
Fact 2 is SUFFICIENT.
Final Answer: D
GMAT assassins aren't born, they're made,
Rich
Timer
00:00
Your Answer
A
B
C
D
E
Global Stats
w^-2 = ?
1) w^-1 =1/2
1/w = 1/2 => w=2.
w^-2 = 1/4.
statement 1) alone is sufficient.
2) w^3 = 8
w=2
w^-2 = 1/4.
statement 2) alone is also sufficient.
Both statements independently are suffcient.
Hence option D is correct.
1) w^-1 =1/2
1/w = 1/2 => w=2.
w^-2 = 1/4.
statement 1) alone is sufficient.
2) w^3 = 8
w=2
w^-2 = 1/4.
statement 2) alone is also sufficient.
Both statements independently are suffcient.
Hence option D is correct.