# Factorial Notation

Home > Counting Techniques Factorial Notations $n!$ is the product of the first $n$ positive integers for $n\ge 1$. $$n!=n(n-1)(n-2)(n-3) \cdots \times 3 \times 2 \times 1$$ $n!$ is read "$n$ factorial". For example, the product $5 \times 4 \times 3 \times 2 \times 1$ can be written as $5!$. Notice that \$5 \times 4 [...]

# Probability with Replacement

Share0 Share +10 Tweet0 Probability with Replacement is used for questions where the outcomes is returned back to the sample space again. Which means that once the item is selected, then it is replace back to the sample space, so the number of elements of the sample space remains unchanged. A jar contains five balls […]

# Probability Ratio using Combination

Share0 Share +10 Tweet0 Counting Techniques for Probability Ratio using Combination The probability ratio of an event is the likelihood of the chance that the event will occur as a result of a random experiment, and it can be found using combination. When the number of possible outcomes of a random experiment is infinite, the […]