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# Math: Number Theory - Percents

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Re: Math: Number Theory - Percents [#permalink]
Yet another great work by Bunuel
Thank you for sharing.
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Re: Math: Number Theory - Percents [#permalink]
I am with ThisisGeero, can you please explain how you came up with the 10/100 in the fraction instead of 8/100?
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Re: Math: Number Theory - Percents [#permalink]
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Kudos
Thanks a lot!

That's just a typo perhaps?
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Re: Math: Number Theory - Percents [#permalink]
Great work Bunuel! Thank you for your efforts!
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Re: Math: Number Theory - Percents [#permalink]
I've added the topic to GMAT ToolKit 1.3.3 and references from the OG12 book.
Thanks, Bunuel!
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Re: Math: Number Theory - Percents [#permalink]
ThisisGeero wrote:
In the Percent Section for the specified example, why is it 2/10 - 10/100 / 2/10 ? Shouldn't it be 2/10 - 8/100 / 2/10 ? Where did the 10/100 come from?

There was a typo - edited. Thanks.
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Re: Math: Number Theory - Percents [#permalink]
Thanks its a big help!!

Kudos!!!

Roy
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Re: Math: Number Theory - Percents [#permalink]
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Bunuel wrote:
PERCENTS

Example: Lena’s grade was in the 80th percentile out of 120 grades in her class. In another class of 200 students there were 24 grades higher than Lena’s. If nobody had Lena’s grade, then Lena was what percentile of the two classes combined?

Solution:
Being in 80th percentile out of 120 grades means Lena outscored $$120*0.8=96$$ classmates.

In another class she would outscored $$200-24=176$$ students.

So, in combined classes she outscored $$96+176=272$$. As there are total of $$120+200=320$$ students, so Lena is in $$\frac{272}{320}=0.85=85%$$, or in 85th percentile.

Attachment:
Math_icon_percents.png

In another class she would outscored $$200-24=176$$ students.
I think it should be 200-24-1 = 175 as 24 were higher than Lena , thus 24+1 are lower than her, we need to count her as well
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Re: Math: Number Theory - Percents [#permalink]
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gurpreetsingh wrote:
Bunuel wrote:
PERCENTS

Example: Lena’s grade was in the 80th percentile out of 120 grades in her class. In another class of 200 students there were 24 grades higher than Lena’s. If nobody had Lena’s grade, then Lena was what percentile of the two classes combined?

Solution:
Being in 80th percentile out of 120 grades means Lena outscored $$120*0.8=96$$ classmates.

In another class she would outscored $$200-24=176$$ students.

So, in combined classes she outscored $$96+176=272$$. As there are total of $$120+200=320$$ students, so Lena is in $$\frac{272}{320}=0.85=85%$$, or in 85th percentile.

Attachment:
Math_icon_percents.png

In another class she would outscored $$200-24=176$$ students.
I think it should be 200-24-1 = 175 as 24 were higher than Lena , thus 24+1 are lower than her, we need to count her as well

I was going to post it, but you already did.
I completely agree with you.
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Re: Math: Number Theory - Percents [#permalink]
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gurpreetsingh wrote:
Bunuel wrote:
PERCENTS

Example: Lena’s grade was in the 80th percentile out of 120 grades in her class. In another class of 200 students there were 24 grades higher than Lena’s. If nobody had Lena’s grade, then Lena was what percentile of the two classes combined?

Solution:
Being in 80th percentile out of 120 grades means Lena outscored $$120*0.8=96$$ classmates.

In another class she would outscored $$200-24=176$$ students.

So, in combined classes she outscored $$96+176=272$$. As there are total of $$120+200=320$$ students, so Lena is in $$\frac{272}{320}=0.85=85%$$, or in 85th percentile.

Attachment:
Math_icon_percents.png

In another class she would outscored $$200-24=176$$ students.
I think it should be 200-24-1 = 175 as 24 were higher than Lena , thus 24+1 are lower than her, we need to count her as well

The point here is that Lena herself is not in the other class. So in another class she outscored 200-24=176 not 175.

Hope it's clear.
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Re: Math: Number Theory - Percents [#permalink]
yes you are right. thanks
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Re: Math: Number Theory - Percents [#permalink]
being new to this forum i found such posts amazingly helpful.. thanks
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Re: Math: Number Theory - Percents [#permalink]
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[quote="Bunuel"]PERCENTS

The Official Guide, 12th Edition: PS #10; PS #17; PS #19; PS #47; PS #55; PS #60; PS #64; PS #78; PS #92; PS #94; PS #109; PS #111; PS #115; PS #124; PS #128; PS #131; PS #151; PS #156; PS #166; PS #187; PS #193; PS #200; PS #202; PS #220; DS #2; DS #7; DS #21; DS #37; DS #48; DS #55; DS #61; DS #63; DS #78; DS #88; DS #92; DS #120; DS #138; DS #142; DS #143;

Dear bunuel,

can you please put inthe corresponding questions in the 11 the edition as well... so that once after going throuhg your notes we can straight away do some quant work on the same topics???

regards,
kyle
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Re: Math: Number Theory - Percents [#permalink]
Excellent resources!
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Re: Math: Number Theory - Percents [#permalink]
Thanks for the effort and good work! Kudos.
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Re: Math: Number Theory - Percents [#permalink]
thanks for sharing!
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Re: Math: Number Theory - Percents [#permalink]
Hello Bunnel,

This is indeed very helpful. Can you please also add a few examples containing cost price, marked price and selling price scenarios.
Thanks
Re: Math: Number Theory - Percents [#permalink]
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