Asked by Nicole

"Scores on the Wechsler IQ test approximate a normal curve with a mean of 100 and a standard deviation of 15.
b. What percentage of IQ scores are below 74?"

I've been working at this for a while now, but when I solve for the z-score, I keep getting a negative number.
z=(74-100)/15 == -1.73

I remember talking about this in class, but can't find it in my notes or textbook, so I would appreciate any help I can get. Thank you in advance!
Answered by Ms. Sue
http://en.wikipedia.org/wiki/Intelligence_quotient
Answered by Nicole
My confusion isn't with the idea of IQ scores, I'm having trouble calculating the z-score when the number given is less than the mean. My answer doesn't make logical sense like it would if the x number was higher than the mean. If you could walk me through that I would appreciate it.
Answered by Nicole
Oops, never mind. I understand what I was doing wrong. Thank you :)
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