Is \(w+h^4\) positive?

This topic has expert replies
Moderator
Posts: 2058
Joined: Sun Oct 29, 2017 4:24 am
Thanked: 1 times
Followed by:5 members

Is \(w+h^4\) positive?

by M7MBA » Sun Apr 25, 2021 2:56 pm

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Is \(w+h^4\) positive?

(1) \(h\) is positive
(2) \(w\) is positive

Answer: B

Source: Official Guide

GMAT/MBA Expert

User avatar
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

Re: Is \(w+h^4\) positive?

by Brent@GMATPrepNow » Mon Apr 26, 2021 4:51 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

M7MBA wrote:
Sun Apr 25, 2021 2:56 pm
Is \(w+h^4\) positive?

(1) \(h\) is positive
(2) \(w\) is positive

Answer: B

Source: Official Guide
Target question: Is w + h^4 positive?

Statement 1: h is positive
Let's TEST some values.
There are several values of w and h that satisfy statement 1. Here are two:
Case a: w = 1 and h = 1. In this case, w + h^4 = 1 + 1^4 = 2. So, w + h^4 IS positive
Case b: w = -3 and h = 1. In this case, w + h^4= -3 + 1^4 = -2. So, w + h^4 is NOT positive
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: w is positive
Important concept: (any number)^(even integer) = a value greater than or equal to 0
Statement 2 tells us that w is some positive number
We can write: w + h^4 = (some positive number) + ( a value greater than or equal to 0)
We can see that w + h^4 positive is definitely positive
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer: B

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
Image