The population of all sample proportions has a normal distri

The population of all sample proportions has a normal distribution if the sample size (n) is sufficiently large. A rule of thumb for ensuring that n is sufficiently large is: (Ch8)

np >= 10

n(1-p) >= 10

np(1-p) <= 10

np >= 10 and n(1-p) <= 10

np >= 10 and n(1-p) >= 10

Solution

The last option is right.

If X a binomial distribution is approximated to normal, the conditions to be satisfied are

np>=10 and n(1-p)>=10