Normal Approximation

Normal Approximation to the Binomial

If:

n · p ≥ 5

n · (1 − p) ≥ 5.

The binomial distribution B(n, p) can be approximated by the normal distribution:

Normal Approximation to the Binomial

Normal Approximation to the Binomial

Example

In a particular city, one in three families have a phone in their home. If 90 families are chosen at random, calculate the probability that at least 30 of them will have a phone.

Normal Approximation to the Binomial

Normal Approximation Operations

Normal Approximation Calculations

Normal Approximation to the Binomial