If m and n are positive integers

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mangomangodolly: Junior | Next Rank: 30 Posts; Posts: 13; Joined: Sun Nov 25, 2012 1:30 am

by mangomangodolly » Mon Nov 26, 2012 9:54 am

If m and n are positive integers, then lcm(m,n) denotes the least common multiple of m and n. Let x be a positive integer and y be a positive integer. What is the value of x?

(1) lcm(x,y) = 5y

(2) lcm(x, lcm(x,y)) = 300

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

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Source: Beat The GMAT — Data Sufficiency | Mon Nov 26, 2012 9:54 am

jkaustubh: Senior | Next Rank: 100 Posts; Posts: 52; Joined: Mon Aug 13, 2012 11:53 pm; Location: Mumbai; Thanked: 1 times

by jkaustubh » Mon Nov 26, 2012 8:29 pm

IMO, the answer can be A

not sure though, what is the OA?

Replying a query takes patience and time. The least a person can do is to thank the reply.

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tinashine20: Junior | Next Rank: 30 Posts; Posts: 13; Joined: Sun Nov 25, 2012 1:14 am

by tinashine20 » Mon Nov 26, 2012 8:45 pm

Please provide official answer, this question is quite intresting.

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sanrisenew: Junior | Next Rank: 30 Posts; Posts: 25; Joined: Fri Jun 08, 2012 7:12 am; Thanked: 1 times

by sanrisenew » Mon Nov 26, 2012 11:33 pm

1. LCM of x,y is 5y ,here we can assume x= 5.a & y = k.a; in this scenario LCM would be 5.k.a= 5y= k.x
Therefore depending on value of a, x can assume multiple values hence insufficient.
2. lcm(x, lcm(x,y)) = lcm(x,y) = 300
for 300 to be lcm of two numbers there are couple of contenders (12,25);(4,75)

hence IMO E

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Tue Nov 27, 2012 4:51 pm

mangomangodolly wrote:If m and n are positive integers, then lcm(m,n) denotes the least common multiple of m and n. Let x be a positive integer and y be a positive integer. What is the value of x?

(1) lcm(x,y) = 5y
(2) lcm(x, lcm(x,y)) = 300

Target question: What is the value of x?

Statement 1: lcm(x,y) = 5y
There are several pairs of numbers that meet this condition. Here are two:
Case a: x=300 and y=60. Here, the LCM is 300, and 300 equals 5y
Case b: x=150 and y=60. Here, the LCM is 300, and 300 equals 5y Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: lcm(x, lcm(x,y)) = 300 There are several pairs of numbers that meet this condition. Here are two:
Case a: x=300 and y=60.
Case b: x=150 and y=60.
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined:
Case a: x=300 and y=60.
Case b: x=150 and y=60.
Since we cannot answer the target question with certainty, the combined statements are not SUFFICIENT

Answer = E

Cheers,
Brent

Last edited by Brent@GMATPrepNow on Thu Sep 03, 2015 1:37 pm, edited 1 time in total.

Brent Hanneson - Creator of GMATPrepNow.com

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J N: Senior | Next Rank: 100 Posts; Posts: 44; Joined: Tue Mar 12, 2013 2:27 pm; Thanked: 3 times

by J N » Fri Mar 22, 2013 12:35 pm

did you mean 150 and 30

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