I have the following equation to solve:

We are going to try to apply the Standard Normal Distribution.

The average IQ for people is 100. The standard deviation is 16. Since I can't give you an IQ test we're going to make one up for each of you.

We'll do that as follows: take your age, divide by 2 and add 100. For this response use that value as your IQ, and determine what percentage of people would have a higher IQ. (e.g. Age = 40 y. Then you would determine percentage of people who have IQ greater than 120.)

This is what I came up with. Can you tell me if this is correct and if not where am I going wrong?

The IQ I am solving for is 44/2 + 100 = 122

122-100/16 = 22/16= 1.375

P(x>122) = P(z>1.375)
P(z>1.375 = 1-P(z<1.375)
= 1-0.9147 = 0.0853 = 8.5% people have an IQ of 122 or higher

This seems good to me. Well done! :)

Quote:

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Originally Posted by zetablue1

P(x>122) = P(z>1.375)
P(z>1.375 = 1-P(z<1.375)
= 1-0.9147 = 0.0853 = 8.5% people have an IQ of 122 or higher

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Are you supposed to be rounding 1.375 down to 1.37 for some reason? The .9147 is for 1.37.

(And do you not have a tail chart so you don't have to do all that re-arranging?)

I don't know what is his table for the distribution. Do all of them contain values of z of up to 4 dp and higher or are there some with only three dp?

I've seen about three different types of charts. The first is the kind I originally learned from. The second is the kind the current book in use at my school uses. (Same book I had but newer version.) That one doesn't do detail after 3.0. That looks to be the kind OP used. I can't find an example of a tail chart. It's like the opposite of the second chart so you don't have to do the subtracting.

http://www.science.mcmaster.ca/psych...e/z-table2.jpg
http://business.statistics.sweb.cz/normal01.jpg

Quote:

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Originally Posted by morgaine300

I've seen about three different types of charts. The first is the kind I originally learned from. The second is the kind the current book in use at my school uses. (Same book I had but newer version.) That one doesn't do detail after 3.0. That looks to be the kind OP used. I can't find an example of a tail chart. It's like the opposite of the second chart so you don't have to do the subtracting.

http://www.science.mcmaster.ca/psych...e/z-table2.jpg
http://business.statistics.sweb.cz/normal01.jpg

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Thanks!

I found that site. The tail chart is named 't chart' here

Distribution Tables

t chart is a different thing, though a t chart does usually seem to be a tail chart. Z is on there - it's the infinity at the bottom.