Question

Some psychologists believe that a "genius" should be defined as anyone having an IQ over 140. If IQ scores are?

normally distributed with a mean of 100 and a standard deviation of 17, and if the population of the world is 6,575,000,000, how many geniuses are there in the world today?

Answer 1

http://answers.yahoo.com/question/index?qid=20090509090635AAcZ2iP

Answer 2

mean = 100
SD = 15
z-value = (140 - 100)/15 = 2.67 to 2 DP

looking up a z- table,
P[IQ >140] = 0.0038 or 0.38%

so estimated # of geniuses = 0.38% of 6,575,000,000

= 24,985,000 [C] <=== ANS

Answer 3

That was wrong, thank you tho.

Answer 4

that's 0.93%

Answer 5

61,147,500