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Normal Distribution

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Normal Distribution

by N:Dure » Mon Dec 13, 2010 6:01 pm
The variable x is normally distributed. The values of x at the 45th, the 15th, and the Kth percentiles of the distribution are 550, 350 and 450 respectively.



Column A
K

Column B
30

A) Column A is bigger
B) Column B is bigger
C) Both are equal
D) Cannot be determined from the information given


I got 30, i.e. both are equal, is this correct?
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by Night reader » Mon Dec 13, 2010 7:12 pm
N:Dure wrote:The variable x is normally distributed. The values of x at the 45th, the 15th, and the Kth percentiles of the distribution are 550, 350 and 450 respectively.



Column A
K

Column B
30

A) Column A is bigger
B) Column B is bigger
C) Both are equal
D) Cannot be determined from the information given


I got 30, i.e. both are equal, is this correct?

45%-15%=30%;
550-350=200;
distr. values to % => 200/30
test 30% => 15%+15%=30% => 350+ 15*(200/30)= 350+100= 450 => choice C
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by N:Dure » Mon Dec 13, 2010 8:28 pm
Night reader wrote:
N:Dure wrote:The variable x is normally distributed. The values of x at the 45th, the 15th, and the Kth percentiles of the distribution are 550, 350 and 450 respectively.



Column A
K

Column B
30

A) Column A is bigger
B) Column B is bigger
C) Both are equal
D) Cannot be determined from the information given


I got 30, i.e. both are equal, is this correct?

45%-15%=30%;
550-350=200;
distr. values to % => 200/30
test 30% => 15%+15%=30% => 350+ 15*(200/30)= 350+100= 450 => choice C

I don't get this part => 15%+15%=30%=> 350+ 15*(200/30) why 15?
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by Night reader » Mon Dec 13, 2010 8:33 pm
N:Dure wrote:
Night reader wrote:
N:Dure wrote:The variable x is normally distributed. The values of x at the 45th, the 15th, and the Kth percentiles of the distribution are 550, 350 and 450 respectively.



Column A
K

Column B
30

A) Column A is bigger
B) Column B is bigger
C) Both are equal
D) Cannot be determined from the information given


I got 30, i.e. both are equal, is this correct?

45%-15%=30%;
550-350=200;
distr. values to % => 200/30
test 30% => 15%+15%=30% => 350+ 15*(200/30)= 350+100= 450 => choice C

I don't get this part => 15%+15%=30%=> 350+ 15*(200/30) why 15?
you are required in B column to measure the k-th percentile as 30% => you are given 15% value in the problem => the residual portion makes 15% => 16%=350+200/30, 17%=350+200/30 + 200/30, ... => 30%=350+15*(200/30)
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by N:Dure » Mon Dec 13, 2010 8:40 pm
Yep, all clear now. Thanks for explaining!
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