(Q). There are 8 questions in an examination. A student has to answer at least four question to pass the exam, in how many ways he can fail in the exam?
Solution:-
Student can fail by answering 0 or 1 or 2 or 3 questions in the exam & this can be done in ⁸C₀ + ⁸C₁ + ⁸C₂ + ⁸C₃ ways.
= 1 + 8 + 28 + 56
= 93 ways Answer
