In the first tutorial I show you what a Binomial Distribution is by considering various different tree diagrams to determine the conditions. You are also introduced to the notation used to describe a random variable that is Binomially distributed.

## Formula

In this tutorial I show you how to calculate binomial probabilities without the need for drawing a tree diagram.

## Examples

Now I look at using the formula in solving the following questions. You may like to try these before looking at the tutorial and worked solution.

(1) The manufacturer of a bag of sweets claims that there is a 90% chance that the bag contains some toffees. If 20 bags are chosen. What is the probability that

(i) all the bags contain toffees?

(ii) more than 18 bags contain toffees?

(2) In clinical trials a certain drug has an 8% success rate of curing a known disease. If 15 people are known to have the disease, what is the probability of at least 2 being cured?