A student is certain of the answers to 4 questions

Jessica Collier

Jessica Collier

Answered question

2022-02-13

A student is certain of the answers to 4 questions but is totally baffled by 6 questions. If the student randomly guesses the answers to those 6 questions, what is the probability that the student will get a score of 5 or more on the test? E

Answer & Explanation

traciaul6y

traciaul6y

Beginner2022-02-14Added 14 answers

Step 1
Let us assume that the student gets the 4 questions which he is certain of correctly.
Now, he randomly guesses the remaining 6 questions, which each have 5 options.
The probability of him getting a particular problem correctly is 15
In order to score a 5 or more, he needs to get at least 1 of the remaining 6 questions correctly. We can find the probability that he gets exactly 1 question correct, 2 questions correct, 3 questions correct, and 6 questions correct. Adding these probabilities will give us the correct answer.
But there is an easier way. We can calculate the probability that he will not get a score of 5 or more and subtract it from 1. In other words, we calculate
1P(all remaining 6 questions wrong)
Assuming that answering the remaining six questions are independent events, we can just multiply the probabilities of getting one question wrong:
145×45×45×45×45×45
=115291562573.79%

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