Question n the attachment

This topic has expert replies
Source: — Data Sufficiency |

User avatar
Legendary Member
Posts: 1100
Joined: Sat May 10, 2014 11:34 pm
Location: New Delhi, India
Thanked: 205 times
Followed by:24 members

by GMATinsight » Sat Mar 05, 2016 7:15 am
eitijan wrote:Source: GMATPrep
Could not understand the statements. Please help me to solve.
let, z = 0.abcd

Question: b=?

Statement 1:tenths digit of 100z is 2

100z = 100*0.abcd = ab.cd
i.e. c = 2
but b is still unknown hence
NOT SUFFICIENT

Statement 2:Unit digit of 1000z is 2
1000z = 1000*0.abcd = abc.d
i.e. c = 2
but b is still unknown hence
NOT SUFFICIENT

Combining the two statements
It still gives us c but not b. Hence,
NOT SUFFICIENT

Answer: Option E
"GMATinsight"Bhoopendra Singh & Sushma Jha
Most Comprehensive and Affordable Video Course 2000+ CONCEPT Videos and Video Solutions
Whatsapp/Mobile: +91-9999687183 l [email protected]
Contact for One-on-One FREE ONLINE DEMO Class Call/e-mail
Most Efficient and affordable One-On-One Private tutoring fee - US$40-50 per hour

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

by Brent@GMATPrepNow » Sat Mar 05, 2016 7:19 am
What is the hundredths digit of the decimal z?

1) The tenths digit of 100z is 2
2) The unit digit of 1000z is 2
Target question: What is the hundredths digit of the decimal z?

Statement 1: The tenths digit of 100z is 2
Notice what happens when we take a decimal like 0.123456 and multiply it by 100.
We get 12.345 (the tenths digit is 3)
In the original decimal, the 3 was in the thousandths place.
So, statement 1 tells us that the THOUSANDTHS digit of z is 2
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: The unit digit of 1000z is 2
Notice what happens when we take a decimal like 0.123456 and multiply it by 1000.
We get 123.45 (the units digit is 3)
In the original decimal, the 3 was in the thousandths place.
So, statement 2 tells us that the THOUSANDTHS digit of z is 2
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

NOTE: Since statements 1 and 2 BOTH tell us the same thing (i.e., the THOUSANDTHS digit of z is 2), the combined statements are NOT SUFFICIENT

Answer = E

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

GMAT/MBA Expert

User avatar
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

by [email protected] » Sat Mar 05, 2016 5:41 pm
Hi eitijan,

The question that you've posted is remarkably similar to the one posted here:

https://www.beatthegmat.com/digit-ds-que ... 80317.html

Read through my explanation, then try taking the same approach with this prompt. I bet that you can solve it.

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image