[ARCHIVED THREAD] - Math probability question help

Posted: 7/23/2005 6:46:10 AM EDT

Find the probability of the result using the normal curve approximation to the bimominal distribution.
240 or more heads out of 500 coin tosses

What am I doing wrong?

mean= 250
std dev = square root of 500 (.50) (..50) = 11.18
z= 240- 250 divided by 11.18 = -.90
z=-.90= .3159
.5-.3159= .1841
.1841+.5= .6841 <----------- should be the answer, right?????????

Posted: 7/23/2005 6:53:43 AM EDT

[#1]

I'm a little fuzzy on probability, but this line:

z=-.90= .3159

How does that one work?

Posted: 7/23/2005 7:02:08 AM EDT

[#2]

Quoted:
I'm a little fuzzy on probability, but this line:

z=-.90= .3159

How does that one work?

You just look up the number off of the z table.

Posted: 7/23/2005 7:13:11 AM EDT

[#3]

When you use the normal to approximate the binomial you must use the continuity correction by taking 239.5 instead of 240. This will slightly change your answer.

(239.5-250)/(125^.5) = -.93915, not -.90

Edited for typo

Posted: 7/23/2005 9:30:48 AM EDT

[#4]

Quoted:
When you use the normal to approximate the binomial you must use the continuity correction by taking 239.5 instead of 240. This will slightly change your answer.

(239.5-250)/(125^.5) = -.93915, not -.90

Edited for typo

That is what I needed, thanks!!!!!

[ARCHIVED THREAD] - Math probability question help

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[ARCHIVED THREAD] - Math probability question help

[ARCHIVED THREAD] - Math probability question help