What is the hundredths digit in the decimal expression of

Question

What is the hundredths digit in the decimal expression of x/55
 
(1) x is the least common denominator of 1/7 and positive integer y 
(2) x is prime.

Bunuel · Accepted Answer

If statement (1) is as you wrote and OA is A then:

(1) x is the least common denominator of 1/7 and positive integer y --> if x is the least common denominator of 1/7 and y/1 (where y is a positive integer) then x must equal to 7 (7 is a least common multiple of 7 and 1), so we can find the hundredths digit of 7/55. Sufficient.
(2) x is prime. Clearly insufficient.

Answer: A.

VeritasPrepBrian · Answer

Hey RXS:

Can you retype Statement 1? You're missing the number/variable before "and", so it's tough to make sense of statement 1.

2 alone is not sufficient, so we can at least get started with that!

Thanks!
Brian

VeritasPrepBrian · Answer

Thank you!

Just one more clarification...I don't think you can have a "least common denominator" of a positive integer, so I'm going to treat this one as:

1) x is the least common denominator of 1/7 and 1/y (with y as a positive integer)

If that's the case, 1 isn't sufficient on its own, as x could be 7, 14, 21, etc. And if you look at what the decimals would be of x/55:

7/55 will be something really small (less than 1/7 and just over 1/8, so maybe around .13)

14/55 will just double that (so maybe around .27)

21/55 will triple the original (.3-something)

So we can tell that the hundredths digit will be different depending on which multiple of 7 x turns out to be.

Together, though, if x is a prime number that's the lowest common denominator of y and 7, then x must be 7 (anything else divisible by 7 is not prime). So x/55 = 7/55, and whatever that hundredths digit turns out to be, there will only be one. So the answer here would be C.

mypatpat · Answer

Could this be a trick question?

While you can't really have a lowest common denominator for an integer y, but you can represent y as y/1 which would yield a lowest common denominator of 7.

rxs0005 · Answer

Guys the OA is A for this Bunuel can u help us on this , from what i gather u can have LCD of a fraction and an integer

amit2k9 · Answer

Bit strange, y can be also written as 14/7, 28/14 or so,giving an integral value.
In that case LCD becomes 7 or more.
Considering this scenario, b definitely comes into picture.
OA becomes C then.

fluke · Answer

If it is written that "y" is +ve integer, it means that y is integer in its simplest form. What you have written is correct but is not in its simplest form.

BTW, I liked VeritasPrepBrian's tweak in the question. Made it more interesting.

gmatopoeia · Answer

From Statement 1 
Least common denominator of 1/7 and positive integer Y/1 ---> 7 
So, x=7
Sufficient

From Statement 2 
possible values of x ---> all prime nos.
Insufficient

Answer: A

jimwild · Answer

You assumed Y is an integer, so what we should do on actual GMAT ? assume uknowns like y are integers? always?

Aleix23 · Answer

Hello
Could someone please explain how do you find the Least Common Denominator of a rational number? (1/7)

I've always used the concept of LCD with integers so it's hard for me to understand it with rationals.

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What is the hundredths digit in the decimal expression of

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