Interestingly, in the real world no statistician would ever calculate standard deviation by hand. The calculations involved are somewhat complex, and the risk of making a mistake is high. Also, …

If you're grouping things by anything other than numerical values, you're grouping them by categories. By learning how to use tools such as bar graphs, Venn diagrams, and two-way tables, you'll expand …

We give you an introduction to probability through the example of flipping a quarter and rolling a die.

A random variable is some outcome from a chance process, like how many heads will occur in a series of 20 flips, or how many seconds it took someone to read this sentence. Calculate probabilities and …

Learn the general multiplication rule for probabilities with interactive exercises and examples on Khan Academy.

Practice finding probabilities of events, such as rolling dice, drawing marbles out of a bag, and spinning spinners.

Think about what probabilities really mean. What does a probability of 0 mean? How about 1?

In this example we are figuring out the probability of randomly picking a non-blue marble from a bag. Again, we'll have to think about the possible outcomes first.

Is this statement about conditional probability true or false? "In general, P (A | B) = P (B | A) . You can reverse the order and the probability is the same either way."

To explain what caused this mass extinction, scientists have focused on events that would have altered our planet's climate in dramatic, powerful ways. The leading theory is that a huge asteroid slammed …