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ggoodwin52
Students
 
Posts: 1
Joined: Wed May 14, 2014 11:06 am
 

Repeating Decimal Question Discrepancy

by ggoodwin52 Mon May 19, 2014 4:37 pm

Hello All,

I need some clarification on the answers to questions involving the equality of repeating decimals. Question 1 in the Math Diagnostic Test in the 5 Lb. book (2013 edition) asks whether 0.01410 (repeating bar over digits right of decimal) or 0.0141 (same repeating bar) is larger. The answer given by the book is that they are equal, which makes perfect sense.

However, this directly contradicts the answer given in the ETS .pdf practice test that is available on the website: https://www.ets.org/s/gre/pdf/practice_ ... l_test.pdf

On page 75 in section 5, question 2, we see the same thing, but the numbers are 0.717 and 0.71 (each repeating). Again, you would thing these would be equal, but here the answer is that 0.717 is larger.

It seems like the way to go would be to follow ETS's answer, but the contradiction between ETS and Manhattan GRE has me unsure of which answer would actually be correct on the exam. Perhaps it's a mistake on ETS's part, as the Manhattan answer is more locial?

Insight is appreciated!

Thanks
tommywallach
Manhattan Prep Staff
 
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Joined: Thu Mar 31, 2011 11:18 am
 

Re: Repeating Decimal Question Discrepancy

by tommywallach Thu May 22, 2014 8:29 pm

Hey Ggoodwin,

You've made a couple of critical errors here.

#1: The question does not put the repeating bar over all the numbers to the right of the decimal in Quantity A. It puts in on the four numbers to the right of the zero. This means that you'll only be repeating 1410 over and over again. So quantity A will look like this: .0141014101410

Quantity B is repeating all four numbers like so: 014101410141

Those are the same.

#2: In the example you gave, the numbers would not be the same.

First we have a series of three repeating numbers: .717717717

Then we have a series of two repeating numbers: 717171

Notice that in the first example, there's a string of two repeated sevens in a row, which is missing from the second example.

Hope that helps!

-t