The ability to create "Answer any N questions" type of test is now available
"Answer any N questions" is a type of test format that allows the test-taker to choose a certain number of questions to answer out of the total number of questions.
N represents the number of questions that the test-taker is expected to answer.
For example, if a test has 10 questions and the test-taker is required to answer any 6 of them, the test-taker has the freedom to choose which 6 questions to answer. The other 4 questions will not be counted and will not have any impact on the test-taker's test score.
To create such a test, go to your Test settings and set the "Automatically excluding questions" to "Section". Then you can browse to your Section's settings and configure how many questions the test-taker is expected to answer in this section.