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# Each of the products produced yesterday was checked by x or

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Each of the products produced yesterday was checked by x or [#permalink]

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15 May 2013, 00:31
4
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Difficulty:

35% (medium)

Question Stats:

70% (01:51) correct 30% (02:39) wrong based on 208 sessions

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Each of the products produced yesterday was checked by x or y. 0.5% of the products checked by x are defective and 0.8% of the products checked by y are defective. If the total defective rate of all the products checked by x and y is 0.75%, what fraction of the products was checked by y?

A. 3/5
B. 5/6
C. 7/11
D. 4/5
E. 5/8
[Reveal] Spoiler: OA

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Re: Each of the products produced yesterday was checked by x or [#permalink]

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15 May 2013, 00:47
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Expert's post
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navigator123 wrote:
Each of the products produced yesterday was checked by x or y. 0.5% of the products checked by x are defective and 0.8% of the products checked by y are defective. If the total defective rate of all the products checked by x and y is 0.75%, what fraction of the products was checked by y?

A. 3/5
B. 5/6
C. 7/11
D. 4/5
E. 5/8

The easiest way to do these types of questions is to look at the difference between x and y on a number line. x is at 0.5 and y is at 0.8, and together the average is 0.75. This means that every product checked by x brings down the average by 0.25 and every product checked by y brings up the average by 0.05. To balance these two out, y needs to check 5 products for every time x checks 1 product. Hence 1/6 of total checked by x and 5/6 of total checked by y.

Algebra works too but the number line strategy gets you the correct answer quickly. If you practice doing that, this is a 1-minute question, from starting to read to clicking "next".

Hope this helps!
-Ron
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Re: Each of the products produced yesterday was checked by x or [#permalink]

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15 May 2013, 01:08
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You can use alligation to solve this.
Ratio X=0.75-0.5=0.25

Ratio Y=0.8-0.75=0.05
Now the ratio y/x is:
$$\frac{Y}{X}=\frac{0.25}{0.05}$$ or $$\frac{5}{1}$$

So for 6 products there were 5 Y and 1 X. 5/6 is the answer
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Re: Each of the products produced yesterday was checked by x or [#permalink]

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15 May 2013, 02:59
3
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2
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navigator123 wrote:
Each of the products produced yesterday was checked by x or y. 0.5% of the products checked by x are defective and 0.8% of the products checked by y are defective. If the total defective rate of all the products checked by x and y is 0.75%, what fraction of the products was checked by y?

A. 3/5
B. 5/6
C. 7/11
D. 4/5
E. 5/8

This is a allegation problem.

We can use a shortcut.

See the attachment for the shortcut.Its a simple one

So X/Y = 0.05/0.25 = 1/5

Therefore the fraction of products checked by Y = 5/6
Attachments

File comment: The shortcut

untitled.JPG [ 4.43 KiB | Viewed 2536 times ]

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Re: Each of the products produced yesterday was checked by x or [#permalink]

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28 Jul 2014, 02:38
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Each of the products produced yesterday was checked by x or [#permalink]

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09 Aug 2014, 01:54
SrinathVangala wrote:
navigator123 wrote:
Each of the products produced yesterday was checked by x or y. 0.5% of the products checked by x are defective and 0.8% of the products checked by y are defective. If the total defective rate of all the products checked by x and y is 0.75%, what fraction of the products was checked by y?

A. 3/5
B. 5/6
C. 7/11
D. 4/5
E. 5/8

This is a allegation problem.

We can use a shortcut.

See the attachment for the shortcut.Its a simple one

So X/Y = 0.05/0.25 = 1/5

Therefore the fraction of products checked by Y = 5/6

Kudos [?]: 2 [0], given: 13

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Re: Each of the products produced yesterday was checked by x or [#permalink]

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16 Dec 2015, 01:11
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

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Re: Each of the products produced yesterday was checked by x or [#permalink]

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16 Dec 2015, 03:51
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Differential approach

---50------------75------80----->

25x=5y

x/y=5/25=1/5, so y/x+y=5/6

B

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Re: Each of the products produced yesterday was checked by x or [#permalink]

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14 Jun 2017, 12:01
1
KUDOS
navigator123 wrote:
Each of the products produced yesterday was checked by x or y. 0.5% of the products checked by x are defective and 0.8% of the products checked by y are defective. If the total defective rate of all the products checked by x and y is 0.75%, what fraction of the products was checked by y?

A. 3/5
B. 5/6
C. 7/11
D. 4/5
E. 5/8

0.5X + 0.8Y = 0.75 ( X + Y )
=> 0.05 Y = 0.25 X
=> Y / X = 5 / 1

Fraction = 5/6

Kudos [?]: 2 [1], given: 4

Re: Each of the products produced yesterday was checked by x or   [#permalink] 14 Jun 2017, 12:01
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