Question 259 of 417MediumMCQ
A multiple choice exam has 5 questions, each with 3 options (1 correct). Find the probability of getting 4 or more correct by guessing.
Solutions · 1
Official solution
p=31,q=32.
\[P(X\ge4) = {}^5C_4\left(\frac13\right)^4\left(\frac23\right)+{}^5C_5\left(\frac13\right)^5 = \frac{10+1}{3^5}=\frac{11}{3^5}\] Answer the question to unlock