BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

What is the value of prime number z?

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
Legendary Member
Posts: 2898
Joined: Thu Sep 07, 2017 2:49 pm
Thanked: 6 times
Followed by:5 members

by Vincen » Mon Jun 25, 2018 12:40 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Hello Gmat_mission.

First of all, we know that z is a prime number.

First Statement
(1) z^3 < 25
We have the following:

- If z=2 then z^3 = 8 < 25.
- If z=3, then z^3 = 27 > 25.

Therefore, the answer is z=2. So, this statement is sufficient.

Second Statement
(2) z^2 > 1
In this case, we have that any prime number z will satisfy that z^2 > 1. So, this statement is not sufficient.

Therefore, the correct answer is the option A.

I hope it helps you. <i class="em em-smiley"></i>
Top
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Mon Jun 25, 2018 2:33 am

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Gmat_mission wrote:What is the value of prime number z?

(1) z^3 < 25
(2) z^2 > 1
Statement 1: z³ < 25
Only one value for z is possible:
z = 2, with the result that z³ = 2³ = 8.
If z is any other prime number, the value of z³ will exceed 25.
Thus, z=2.
SUFFICIENT.

Statement 2: z² > 1
Here, z can be ANY PRIME NUMBER, since the square of any prime number will be greater than 1.
Since the value of z cannot be determined, INSUFFICIENT.

The correct answer is A.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
User avatar
GMAT Instructor
Posts: 1462
Joined: Thu Apr 09, 2015 9:34 am
Location: New York, NY
Thanked: 39 times
Followed by:22 members

by Jeff@TargetTestPrep » Tue Jun 26, 2018 5:26 pm

Timer

00:00

Your Answer

A

B

C

D

E

Global Stats

Gmat_mission wrote:What is the value of prime number z?

(1) z^3 < 25
(2) z^2 > 1
Solution:

We are given that z is a prime number and we need to determine its value.

Statement One Alone:

z^3 < 25

Since the only prime whose cube is less than 25 is 2, then z must be 2 (notice that if z ≥ 3, then z^3 ≥ 27). Statement one alone is sufficient.

Statement Two Alone:

z^2 > 1

Since any prime number raised to the second power is greater than 1, z could be any prime number. Statement two alone is not sufficient.

Answer: A

Jeffrey Miller
Head of GMAT Instruction
[email protected]

Image

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews
Top
Post new topic Post Reply
• Page 1 of 1