How many different tests can be made from a test bank of 20 questions if the test consists of 5 questions?

Answer 1

Hi Em!

Assuming that the order matters (for example, that a test is considered to be different if a certain question is placed first rather than last), then we can just multiply numbers together like this: 20 * 19 * 18 * 17 * 16 = 1,860,480 different tests. This is because for the first question there are 20 to choose from, leaving 19 to choose from for the second question, etc. for a total of five questions.

Note that if using a calculator such as the TI 84 Plus, there is a function called nPr that could be used to do this instead. First enter 20, then choose the nPr function (usually found by pressing the MATH button and looking under the PROB menu), then entering 5.

Please let me know if I can be more helpful!

Joe