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anartey: Newbie | Next Rank: 10 Posts; Posts: 1; Joined: Sat Apr 02, 2011 12:14 pm

by anartey » Sat Apr 02, 2011 12:18 pm

If r is represented by the decimal 0.t5 what is the digit t ?

1) r < 1/3
2) r < 1/10

Can't seem to wrap my mind around the solution. Thanks for your help.

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Source: Beat The GMAT — Data Sufficiency | Sat Apr 02, 2011 12:18 pm

ldoolitt: Master | Next Rank: 500 Posts; Posts: 184; Joined: Sat Apr 14, 2007 9:23 am; Location: Madison, WI; Thanked: 17 times

by ldoolitt » Sat Apr 02, 2011 6:17 pm

Interesting, I've never seen a problem like this before but I'll give it a shot...

Looking at it from the set perspective (which is my preferred strategy), the allowable set from the stem is

{.95, .85, .75, ..., .05}

Lets see how each of the statements alter that

(1) r < 1/3
this lessens the set to

{.25, .15, .05}

this is insufficient since the set still contains multiple values

(2) r < 1/10
the set is now

{.05}

there is a single number left in the possible set (this statement restricts t to 0) so this is sufficient.

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MAAJ: Master | Next Rank: 500 Posts; Posts: 243; Joined: Sun Jul 12, 2009 7:12 amFollowed by: 2 members; Location: Dominican Republic; Thanked: 31 times; GMAT Score:480

by MAAJ » Sun Apr 03, 2011 7:13 am

Edit: Now that I think about it, I would pick (C) 'cause the decimal 0.t5 doesn't have the minus sign (-) before 0, thus I guess it should be a positive decimal...

IMO [spoiler](E)[/spoiler], BUT if there's a constraint that "r" must be a positive number, then I would change my answer to [spoiler](C)[/spoiler]

r = 0.t5(decimal) t=?

1) r < 1/3
r < 0.33...

r could be 0.25, 0.15, 0.05, -0.05, -0.15, -0.25, -0.35 etc...
So t could be any number...

2) r < 1/10
r < 0.10

r could be 0.05, -0.05, -0.15, -0.25, -0.35 etc...
So t could be again any number...

1) and 2) Combined:
r could be 0.05, -0.05, -0.15, -0.25, -0.35 etc...
As we saw, t could be any number...

anartey wrote:If r is represented by the decimal 0.t5 what is the digit t ?

1) r < 1/3
2) r < 1/10

Can't seem to wrap my mind around the solution. Thanks for your help.

"There's a difference between interest and commitment. When you're interested in doing something, you do it only when circumstance permit. When you're committed to something, you accept no excuses, only results."

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ldoolitt: Master | Next Rank: 500 Posts; Posts: 184; Joined: Sat Apr 14, 2007 9:23 am; Location: Madison, WI; Thanked: 17 times

by ldoolitt » Sun Apr 03, 2011 12:27 pm

MAAJ wrote:Edit: Now that I think about it, I would pick (C) 'cause the decimal 0.t5 doesn't have the minus sign (-) before 0, thus I guess it should be a positive decimal...

Yeah I don't think that a digit has a sign and thus can't change the sign of the entire number. But I may be wrong...

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