● Bernoulli trials, if ... - 1. There are two possible outcomes. 2. The probability of success is constant. 3. The trials are independent. ● Geometric probability model - A Geometric model is appropriate for a random variable that counts the number of Bernoulli trials until the first success. ● Binomial probability model - A Binomial model is appropriate for a random variable that counts the number of successes in a fixed number of Bernoulli trials. ● 10% Condition - When sampling without replacement, trials are not independent. It’s still okay to proceed as long as the sample is smaller than 10% of the population. Success/Failure Condition - For a Normal model to be a good approximation of a Binomial model, we must expect at least 10 successes and 10 failures.