If b is an integer, is 1.3 multiplied by b an integer?

Question

(1) b is a multiple of 3. 
(2) 0.7 multiplied by b is an integer.

GMATWhizTeam · Answer

Step 1: Analyze Question Stem 
 • We know that b is an integer.
• We need to find out, if 1.3 * b = integer or not.
 o Now 1.3 can be written as  \frac{13}{10} 
  Thus,  \frac{13}{10} * b  will be an integer, only when b is a multiple of 10 (For example, 10,20, 30…and so on).

Keeping this in mind, let’s analyze the statements.

Step 2: Analyze individual statements

Statement 1:  b is a multiple of 3.
 • Now, b could be 3 or 6 or 9 or 30.
 o If b = 3, then 1.3*b is not an integer.
o If b = 30, then 1.3*b is an integer.  
Since, we are getting two different answers, statement 1 is not sufficient and we can eliminate answer options A and D.

Statement 2:  0.7 multiplied by b is an integer.
 • That means  \frac{7}{10}  * b = integer.
  This is only possible, when b is a multiple of 10 (For example, 10,20, 30…and so on).
 o And this is what we needed to find out.   
Hence, statement 2 is sufficient but statement 1 is not and the correct answer is  Option B .

bumpbot · Answer

Automated notice from GMAT Club BumpBot: 

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

 This post was generated automatically.

If b is an integer, is 1.3 multiplied by b an integer?

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards