Normal Distribution

[deevicsm]

Can someone give me some feedback on this? Please. SAT Scores are distributed normally with a mean of 500 and a standard deviation of 100. What percentage of people who take the test score above 700? This is what I got is it correct? Z=700-500100=2=.0228 Then you take 1.00-.0228=.9772100=97.72% or is it .0228 100 = 02.28%

What percentage of people scored above 600? When I work this one out it is less than the 700 I get 84.13% or would it be 15.87%

What percentage scored below 350 - I get 6.68% doing the same math as above.

Now here is the tricky one what percentage scored between 450 and 570? I get 25.80% and 19.15% added together is 44.95% all together.

thanks

 

[tkhunny]

Z=(700-500)/100=2=.0228

First, never write that again. Think about it just for a moment. Is 2 = .0228? I think not.

The mean is 500. The percentage scoring over 600 MUST be less that 1/2.

Try to be consistent in your application or basic principles.

 

[deevicsm]

normal distribution

I believe I have decided the answers to all my questions are as follows can someone give me feedback as to if they are correct?

Z = (700-500)/100 = 2 0.0228 x 100 = 2.28% score above 700

What percentage of people score above 600?
Z = (600-500)/100= 1 0.1587 x 100 = 15.87% score above 600

What percentage of people score below 350?
Z = (350-500)/100 = -1.5 .0668 x 100 = 6.68% score below 350

What percentage score between 450 and 570?
Z = (570-500)/100 = 0.70 .2580x100 = 25.80%

Z = (450-500)/100 = -0.500 .1915x100 = 19.15%


25.80% + 19.15% = 44.95% score between 450 and 570

 

[tkhunny]

I believe you have it.

Good call!!