Variation 1 · answer guide

Binomial distribution — Complement form with n=5

Question

If and , which is true?

This practice question was inspired by Question 6 in the 2021 NSW HSC Mathematics Extension 1 examination, © NESA. It is an original TestMum variation that practises the same mathematical idea, not an official NESA question.

Set up the solution: identify the random variable and its parameters before using the matching probability formula..
Match the result to the choices and state the correct option.Therefore option A is correct.

Common mistake: changing so many features that the new example no longer tests the same mathematical idea.

Verification: Even a single success is almost certain with five trials at .

Any mark labels are a TestMum study aid, not an official NESA marking allocation.