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The variable x takes on integer values between 1 and 7 inclu

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The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 08 Jan 2013, 20:25
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X frequency
1 3
2 1
3 3
4 1
5 3
6 1
7 3

The variable x takes on integer values between 1 and 7 inclusive as shown above. What is the probability that the absolute value of the difference between the mean of the distribution which is 4 and a randomly chosen value of x will be greater than 3/2?

A) 8/15
B) 4/7
C) 4/5
D) 6/7
E) 8/7
[Reveal] Spoiler: OA

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Last edited by fozzzy on 09 Jan 2013, 02:43, edited 1 time in total.
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Re: The variable X takes on integer values [#permalink] New post 08 Jan 2013, 21:26
The set is
1,1,1,2,3,3,3,4,5,5,5,6,7,7,7

The question basically asks for the probability of choosing 1,2,6 or 7.

= 8/15
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Re: The variable X takes on integer values [#permalink] New post 08 Jan 2013, 21:47
MacFauz wrote:
The set is
1,1,1,2,3,3,3,4,5,5,5,6,7,7,7

The question basically asks for the probability of choosing 1,2,6 or 7.

= 8/15


Hi Can you please explain in detail?

how u got the values of set?
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Re: The variable X takes on integer values [#permalink] New post 08 Jan 2013, 21:58
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bhavinshah5685 wrote:
MacFauz wrote:
The set is
1,1,1,2,3,3,3,4,5,5,5,6,7,7,7

The question basically asks for the probability of choosing 1,2,6 or 7.

= 8/15


Hi Can you please explain in detail?

how u got the values of set?


Looking at the table.,

The column on the left shows the value of X and the column on the right shows the number of times the value appears. The question statement is just beating around the bush a lot to ask a simple question. What is the probability that 4 - X > 1.5. For such a case, X has to be 1,2,6 or 7.
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Re: The variable X takes on integer values [#permalink] New post 09 Jan 2013, 19:47
MacFauz wrote:
bhavinshah5685 wrote:
MacFauz wrote:
The set is
1,1,1,2,3,3,3,4,5,5,5,6,7,7,7

The question basically asks for the probability of choosing 1,2,6 or 7.

= 8/15


Hi Can you please explain in detail?

how u got the values of set?


Looking at the table.,

The column on the left shows the value of X and the column on the right shows the number of times the value appears. The question statement is just beating around the bush a lot to ask a simple question. What is the probability that 4 - X > 1.5. For such a case, X has to be 1,2,6 or 7.


Hi MacFauz,
I guess answer is correct but the solution seems to be different to me. Pls correct me!

given absolute difference is
|4-X| >1.5
so
-1.5> |4-X| >1.5
solving this
2.5 < X < 6.5
This gives range from
3,3,3,4,5,5,5,6

Anyways, answer will be 8/15.

Actually i did this wrong. On seeing ur solution i got it :lol:
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Re: The variable X takes on integer values [#permalink] New post 09 Jan 2013, 20:27
shanmugamgsn wrote:
MacFauz wrote:
bhavinshah5685 wrote:
The set is
1,1,1,2,3,3,3,4,5,5,5,6,7,7,7

The question basically asks for the probability of choosing 1,2,6 or 7.

= 8/15

Hi Can you please explain in detail?

how u got the values of set?


Looking at the table.,

The column on the left shows the value of X and the column on the right shows the number of times the value appears. The question statement is just beating around the bush a lot to ask a simple question. What is the probability that 4 - X > 1.5. For such a case, X has to be 1,2,6 or 7.


Hi MacFauz,
I guess answer is correct but the solution seems to be different to me. Pls correct me!

given absolute difference is
|4-X| >1.5
so
-1.5> |4-X| >1.5
solving this
2.5 < X < 6.5
This gives range from
3,3,3,4,5,5,5,6

Anyways, answer will be 8/15.

Actually i did this wrong. On seeing ur solution i got it :lol:


The step in red is incorrect. You should note that the least value that |4-X| can take is 0. So, it can never be less than -1.5. The inequality should actually be X<2.5 or X>5.5.
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Re: The variable X takes on integer values [#permalink] New post 09 Jan 2013, 21:53
Actually it should be
-1.5> 4-X >1.5 (it was a typo above)

But still i didnt get u!
|4-X| can be zero ?
then |4-X|>1.5 will be 0>1.5

This isnt wrong?

Messed up :o
Pls explain
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Re: The variable X takes on integer values [#permalink] New post 09 Jan 2013, 21:58
shanmugamgsn wrote:
Actually it should be
-1.5> 4-X >1.5 (it was a typo above)

But still i didnt get u!
|4-X| can be zero ?
then |4-X|>1.5 will be 0>1.5

This isnt wrong?

Messed up :o
Pls explain

I guess I wasn't clear. What I meant to say was that a modulus value cannot be negative. Of course in this question, we want only values for which |4-X|>1.5. The range that you have given (-1.5> 4-X >1.5) is not a valid one. A number cannot be both greater than 1.5 and lesser than -1.5. Rather the interval should be 1.5 < 4-X OR 4-X < -1.5
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Re: The variable X takes on integer values [#permalink] New post 10 Jan 2013, 19:05
MacFauz wrote:
shanmugamgsn wrote:
Actually it should be
-1.5> 4-X >1.5 (it was a typo above)

But still i didnt get u!
|4-X| can be zero ?
then |4-X|>1.5 will be 0>1.5

This isnt wrong?

Messed up :o
Pls explain

I guess I wasn't clear. What I meant to say was that a modulus value cannot be negative. Of course in this question, we want only values for which |4-X|>1.5. The range that you have given (-1.5> 4-X >1.5) is not a valid one. A number cannot be both greater than 1.5 and lesser than -1.5. Rather the interval should be 1.5 < 4-X OR 4-X < -1.5



Thanks MacFauz...
ya i got my mistake in Inequalities.
Thanks dude...
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The variable x takes on integer [#permalink] New post 28 Mar 2013, 23:32
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Re: The variable x takes on integer [#permalink] New post 28 Mar 2013, 23:51
x has values between 1 and 7 so |4-x|>\frac{3}{2}=

|4-1|=3>3/2
|4-2|=2>3/2
|4-3|=1>3/2
|4-4|=0>3/2
|4-5|=1>3/2

|4-6|=2>3/2
|4-7|=3>3/2

The value that respect |4-x|>3/2 are 1,2,6,7 that have a frequency of 3,1,1,3 so 3+1+1+3 = total frequencies of "right" events, and this will be our numerator.
Our denominator will be the tot number of combinations = 3+1+3+1+3+1+3= 15.
Answer \frac{8}{15}
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Re: The variable x takes on integer [#permalink] New post 29 Mar 2013, 01:20
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Re: The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 18 Jul 2013, 02:44
I have a question regarding the denominator 15 : why do we take into consideration the value 4 since it occurs only once and we're looking for the the difference between this value and the others. I had the answer wrong because I assumed the denominator was 14 - could someone try to explain? :oops:
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Re: The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 18 Jul 2013, 06:50
aa81 wrote:
I have a question regarding the denominator 15 : why do we take into consideration the value 4 since it occurs only once and we're looking for the the difference between this value and the others. I had the answer wrong because I assumed the denominator was 14 - could someone try to explain? :oops:


The question states

What is the probability that the absolute value of the difference between the mean of the distribution which is 4 and a randomly chosen value of x will be greater than 3/2?

you get 15 when you add the frequency ( 3+1+3 etc)

The set is

The set is
1,1,1,2,3,3,3,4,5,5,5,6,7,7,7

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Re: The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 18 Jul 2013, 07:41
fozzzy wrote:
X frequency
1 3
2 1
3 3
4 1
5 3
6 1
7 3

The variable x takes on integer values between 1 and 7 inclusive as shown above. What is the probability that the absolute value of the difference between the mean of the distribution which is 4 and a randomly chosen value of x will be greater than 3/2?

A) 8/15
B) 4/7
C) 4/5
D) 6/7
E) 8/7


How can the probability of doing something be 3/2?

How can the probability of doing something be greater than 1?

I don't understand what y'all are calculating.
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Re: The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 18 Jul 2013, 08:29
knightofdelta wrote:

How can the probability of doing something be 3/2?

How can the probability of doing something be greater than 1?

I don't understand what y'all are calculating.


The final answer is below 1

8/15 = 0.5333
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Re: The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 18 Jul 2013, 08:35
fozzzy wrote:
knightofdelta wrote:

How can the probability of doing something be 3/2?

How can the probability of doing something be greater than 1?

I don't understand what y'all are calculating.


The final answer is below 1

8/15 = 0.5333


Then the answer should be 0 since the answer will be below 3/2. 3/2 is higher than 1 and the answer is below 1. Therefore, since the answer is certainly below 1 and 1 is below 3/2, then the answer is 0. And 0 is not one of the answer choices.

Summary: the question is faulty.
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Re: The variable x takes on integer values between 1 and 7 inclu [#permalink] New post 21 Jul 2013, 01:41
Expert's post
knightofdelta wrote:
fozzzy wrote:
knightofdelta wrote:

How can the probability of doing something be 3/2?

How can the probability of doing something be greater than 1?

I don't understand what y'all are calculating.


The final answer is below 1

8/15 = 0.5333


Then the answer should be 0 since the answer will be below 3/2. 3/2 is higher than 1 and the answer is below 1. Therefore, since the answer is certainly below 1 and 1 is below 3/2, then the answer is 0. And 0 is not one of the answer choices.

Summary: the question is faulty.


Please read the question carefully. The question asks "what is the probability that SOME VALUE will be greater than 3/2?" not "is the probability of SOME EVENT greater than 3/2?"
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Re: The variable x takes on integer values between 1 and 7 inclu   [#permalink] 21 Jul 2013, 01:41
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