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At the beginning of January 2003, Elizabeth invested money

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At the beginning of January 2003, Elizabeth invested money

by AAPL » Thu Aug 02, 2018 5:00 am

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B

C

D

E

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At the beginning of January 2003, Elizabeth invested money in an account that collected interest, compounding more frequently than a year. Assume the annual percentage rate of interest remained constant. What is the total amount she has invested after seven years?

(1) her initial investment was $20,000
(2) the account accrued 7% annual interest

The OA is E.
Last edited by AAPL on Thu Aug 09, 2018 5:28 am, edited 1 time in total.
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Source: — Data Sufficiency |

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by Brent@GMATPrepNow » Thu Aug 02, 2018 9:56 am

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AAPL wrote:Source: GMAT Club Tests
Statement 1 is sufficient alone. If we know that x and y are primes then obviously we can determine the number of factors of n. Total factors are (5+1)*(7+1)=48. But unfortunately, the OA is C.

Where is my mistake? Can anyone help me to understand the fact, please? Thanks!
Statement 1 tells us that x and y are primes, but it doesn't tell us that x and y are DIFFERENT primes.
So, for example, if x = y = 2, then n = (2^5)(2^7) = 2^12, and 2^12 has 13 positive divisors.
Conversely, if x = 2 and y = 3, then n = (2^5)(3^7), which has 48 positive divisors.
So, statement 1 is not sufficient.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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