Variation 3 · answer guide

Binomial distribution — Nearly certain

Question

If and , which best describes ?

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., which is essentially and certainly greater than .
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: is negligible.

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