Need help with a college statistic question. Anyone interested?

T

The Sponge

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Here is the question

Weights of 15-year old males
The mean weight of 15 year old males is 142 lbs, and the standard deviation is 12.3 lbs. If the sample of thirty six 15 year old males is selected, find the probability that the mean of the sample will be greater than 144.5 lbs. Assume the variable is normally distributed. Based on your answer would you considered the group overweight? Please show the work on how you arrived at your answer. I know the answer but need to see the work. Thanks:shrug:
 
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kosar

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The Sponge said:
Here is the question

Weights of 15-year old males
The mean weight of 15 year old males is 142 lbs, and the standard deviation is 12.3 lbs. If the sample of thirty six 15 year old males is selected, find the probability that the mean of the sample will be greater than 144.5 lbs. Assume the variable is normally distributed. Based on your answer would you considered the group overweight? Please show the work on how you arrived at your answer. I know the answer but need to see the work. Thanks:shrug:
Click to expand...

WTF? No, not interested.
 
T

The Sponge

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Agent 0659 said:
The mean weight of 15 yr old males is 142 lbs? BS
Click to expand...

cmon man here is what i got so far


u=142 lbs.

o=12.3 lbs
N=36
x=144.5 lbs.

z=x-u
o/the square root of N

=144.5-142
12.3 divided by the square root of144.5
=2.5
12.3 divided by 12.02
= 2.5
1.023
=2.443
.5000-2.443 =-1.943
=1.94
.5000-.4738=.0262 or 2.6%

The correct answer is 0.1112 What am i doing wrong?:shrug: Thanks
 
Agent 0659

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KotysDad

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Sponge,

N = 36, so the sqrt(N) = 6.

It looks to me like you're taking N = 144.5. I think N is the sample size (36).

It might make your calculations come out right. I cant remember all the t-distribution stuff to even attempt this without digging up my old college text books, but at first glance check your value of N.
 
MadJack

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KotysDad said:
Sponge,

N = 36, so the sqrt(N) = 6.

It looks to me like you're taking N = 144.5. I think N is the sample size (36).

It might make your calculations come out right. I cant remember all the t-distribution stuff to even attempt this without digging up my old college text books, but at first glance check your value of N.
Click to expand...
 
M

marine

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The Sponge said:
cmon man here is what i got so far


u=142 lbs.

o=12.3 lbs
N=36
x=144.5 lbs.

z=x-u/
(o/the square root of N)

=144.5-142 /
12.3 divided by the square root of 36

now try doing the calculations rookie.



=2.5
12.3 divided by 12.02
= 2.5
1.023
=2.443
.5000-2.443 =-1.943
=1.94
.5000-.4738=.0262 or 2.6%

The correct answer is 0.1112 What am i doing wrong?:shrug: Thanks
Click to expand...

see above for proper math, rookie
 
T

The Sponge

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KotysDad said:
Sponge,

N = 36, so the sqrt(N) = 6.

It looks to me like you're taking N = 144.5. I think N is the sample size (36).

It might make your calculations come out right. I cant remember all the t-distribution stuff to even attempt this without digging up my old college text books, but at first glance check your value of N.
Click to expand...

Thanks were gonna pick it up after tomorrow. U are correct with ur assessment. found that out on another site. Thanks.
 
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