Final answer:
The probability density function (PDF) for the length of time it takes students to complete a statistics examination, which follows a uniform distribution between 40 and 60 minutes, is 0.05.
Step-by-step explanation:
The length of time it takes students to complete a statistics examination follows a uniform distribution between 40 and 60 minutes. In a uniform distribution, the probability density function (PDF) is constant within the range of values and 0 outside of that range.
Since the range of values is from 40 to 60, the width of the range is 60 - 40 = 20. The PDF is calculated by dividing 1 by the width of the range, so the PDF for this distribution is 1/20 = 0.05.