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There are 40 marbles in a jar. If of the marbles are blue

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GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
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There are 40 marbles in a jar. If of the marbles are blue [#permalink]  09 Dec 2017, 18:38
Expert's post
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Question Stats:

100% (00:57) correct 0% (00:00) wrong based on 5 sessions
There are 40 marbles in a jar. If $$\frac{1}{5}$$ of the marbles are blue, $$\frac{1}{4}$$ of the remaining marbles are red, and 10 marbles are green. If a marble is selected at random, then what is the probability that the marble will not be blue, red, or green?

Drill 2
Question: 10
Page: 529

[Reveal] Spoiler: OA
$$\frac{14}{40}$$

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Sandy
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GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 93

Kudos [?]: 1659 [0], given: 396

Re: There are 40 marbles in a jar. If of the marbles are blue [#permalink]  29 Dec 2017, 15:29
Expert's post
Explanation

First figure out how many marbles of each color are in the jar.

For blue:$$\frac{1}{5}$$ of 40 is 8, so there are 8 blue marbles and 32 other marbles.

For red: $$\frac{1}{4}$$ of 32 is 8, so there are 8 red marbles and 24 marbles that are neither red nor blue. As there are 10 green marbles, there are
14 marbles left that are not green, red, or blue.

Thus, the probability of selecting one of those marbles is $$\frac{14}{40}$$.

If you answered $$\frac{26}{40}$$, you found the probability that the selected marble will be blue, red, or green.

If you answered $$\frac{12}{40}$$, for the red marbles you perhaps found $$\frac{1}{4}$$ of 40 (the total marbles) rather than of 32 (the remaining marbles after blue) in the original calculation.
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Sandy
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Re: There are 40 marbles in a jar. If of the marbles are blue [#permalink]  09 Feb 2018, 07:03
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Are we suppose to write answer as 7/20 or 14/40?
GMAT Club Legend
Joined: 07 Jun 2014
Posts: 4749
GRE 1: Q167 V156
WE: Business Development (Energy and Utilities)
Followers: 93

Kudos [?]: 1659 [1] , given: 396

Re: There are 40 marbles in a jar. If of the marbles are blue [#permalink]  09 Feb 2018, 15:24
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Expert's post
achirarulz wrote:
Are we suppose to write answer as 7/20 or 14/40?

In GRE you are allowed to use both the fractions unless it is mentioned to reduce to lowest terms in which case it is $$\frac{7}{20}$$
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Sandy
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Intern
Joined: 05 Oct 2017
Posts: 10
Followers: 0

Kudos [?]: 7 [0], given: 1

Re: There are 40 marbles in a jar. If of the marbles are blue [#permalink]  21 Feb 2018, 10:01
thank you

sandy wrote:
achirarulz wrote:
Are we suppose to write answer as 7/20 or 14/40?

In GRE you are allowed to use both the fractions unless it is mentioned to reduce to lowest terms in which case it is $$\frac{7}{20}$$
Re: There are 40 marbles in a jar. If of the marbles are blue   [#permalink] 21 Feb 2018, 10:01
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