Question 1194452
If there are two outcomes with constant probability
if np and n(1-p) are > 5 (some use 10)
Do this where large factorials might occur and cannot be calculated.
A batter is hitting 0.400. In the next 200 at bats, what is the chance of his getting 90 or more hits.
With the binomial, this is 200C50 *0.4^90*0.6^110, and that is only for 90 hits. One has to calculate 91, 92,
Normal approximation np=80 (mean)
np(1-p)=80*0.6=48 (variance)
sqrt 48 is 6.93
want z>(89.5-80)/6.83, and that is a lot easier to do.