A common question when dealing with probability density functions (p.d.f.) is to find the constant k. In the first video I show you how to handle a p.d.f. with just one function and then in the second video how to handle two or more functions in a p.d.f.

You will also be shown that if you have a geometrical shape such as a trapezium or triangle in the graph then it can often be quicker to use the area of the shape rather than work through the integral.

## Working with one function in the p.d.f.

## Working with two or more functions in the p.d.f.