On a multiple-choice exam with three possible answers for each of the five questions, what is the probability that a student wou

Question

3 years ago

13

ld get fouror more correct answers just by guessing?

1 answer:

yulyashka [42] · Answer 1 · 2022-03-29T07:36:06+03:00

Answer: 11/243

Step-by-step explanation:

Each question has 3 options: 2 incorrect and 1 correct

Probability P(correct guessing) = 1/3

P(wrong guessing) = 2/3

Probability P(4 answers correct) = 5C4 × (1/3)^4 ×(2/3)^1

Probability P(5 answers guessed correctly) =5C5 ×( 1/3)5

Therefore Probability P(4 or more answers correct) = P(4) + P(5) = (10/3^5) +( 1/3^5)

P(4 or more correct answers) = 11/243