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 13 and if the population of the world is 6,575,000,000, how many geniuses are there in the world today?
A. 123,000
B. 24,985,000
C. 536,000,000
D. 115,000
E. 7,232,500

Answer 1

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 2

IQ of 140 is 3.07 standard deviations above the mean which constitutes .11% of the population, hence, 7,232,500.

Answer 3

??

Answer 4

XD

Answer 5

is it right?

Answer 6

i love you guys take the answer

Answer 7

lol hehe