If s is a decimal of the form D.D0D0, what is s?

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AAPL: Moderator; Posts: 2640; Joined: Sun Oct 29, 2017 2:08 pmFollowed by: 2 members

by AAPL » Mon Oct 30, 2017 9:34 am

If s is a decimal of the form D.D0D0, what is s?

(1) D + D is not single digit.
(2) 2s > 10.

The OA is E.

Please, can any expert explain this DS question for me? I don't have it clear. Thanks.

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Source: Beat The GMAT — Data Sufficiency | Mon Oct 30, 2017 9:34 am

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ErikaPrepScholar: Legendary Member; Posts: 503; Joined: Thu Jul 20, 2017 9:03 amFollowed by: 15 members; Thanked: 86 times; GMAT Score:770

by ErikaPrepScholar » Tue Oct 31, 2017 9:58 am

We know that for s to have the form D.D0D0, D must be an integer from 1-9. So s could be 1.1010, 2.2020 ... 9.9090. For a statement to be sufficient, we must be able to determine what integer D is.

Statement 1

If D+D is not a single digit, this means that D+D must be greater than or equal to 10, making D greater than or equal to 5. However, D can still be 5, 6, 7, 8, or 9. Insufficient.

Statement 2

If 2s > 10, s > 5. This means that s could be 5.5050, 6.6060, 7.7070, 8.8080, or 9.9090. So Statement 2 tells us the exact same thing as Statement 1. Insufficient.

Both

Since both statements tells us the same thing, putting them together doesn't do us any good. So the correct answer is E.

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