suppose 500 coins are tossed using the normal curve approximation, find the probability of
getting exactly 250 heads
Solution
answer is 0.032 as there's an equal probability of heads and tails. In the binomial
distribution, p = 0.5, the number of "successes", i.e. heads. Also you have n = 500, the number
of trials. The mean of this binomial distribution is np = 250 and the variance is np(1 - p) = 125.
Standard deviation = sqrt(variance) = 11.2 For large n, it can be approximated by a normal
distribution of the same mean and variance. I'm not going to do it for you, but it involves
calculating a value usually called z and looking up a table of the standard normal distribution.