Quote:
Originally Posted by ivegotstylekid
yea i got it (55.5-50)/5= a z score of .9 look that up on the positive z score table to get a probability to the left of .8159. subtract 1-.8159=.1814
55.5=at least 55
50=probabilty (.5) times sample 100
5 = square root of sample (100)*probability of heads(.5)*probability of tails(5)
confusing but its broken down
That's the correct normal approximation, but 1 - .8149 = .1841 not .1814, and this would be correct for 55 OR GREATER which uses 54.5 instead of GREATER THAN 55 which uses 55.5. The approximation for GREATER THAN 55 comes out to about .135666. These are both excellent approximations as the exact answers (from Excel function 1-BINOMDIST) are about .18406 and .13562.