To calculate this we can also use the combinations formula on our graphing calculator. We start by entering the number of questions on the test.
Next, push the MATH button, scroll to PRB, and choose the third option. We finish by entering the number of questions we want to answer.
b
This time, the first three questions are mandatory. This means we want to calculate the number of combinations we can choose of 7 questions from a set of 9. Similarly as in Part A, we get the following result.
When the first three exercises are mandatory, there are 36 different ways we can pick the remaining 7 questions.
