Question

Guessing on Exams Suppose, you are taking an exam with 10 questions and you are required to get 7 or more right answers to pass.

With a 10-question true/false test, what is the probability of getting at least 7 answers correct by guessing? With a 10-question multiple-choice test where there are three possible choices for each question, what is the probability of getting at least 7 answers correct by guessing? Only one of the choices is correct for each question. With a 10-question multiple-choice test where there are five possible choices for each

question, only one of which is correct, what is the probability of getting at least 7 answers correct by guessing? d. Which test (of those described in parts a, b, and c in this exercise) would be easiest to pass by guessing, which would be hardest, and why?

Answer 1

Hello Sir/ mam

Given that :

n = 10

To pass we need atleast 7 correct answers.

Now,

(a) True\ False test :

Getting a particular answer correct by guessing have probability = 0.5

Hence,

Now, we know that, for binomial distribution:

Hence, using above formula and putting the values:

(b) MCQ test with 3 possible choices :

Getting a particular answer correct by guessing have probability = 0.33

Hence,

(c) MCQ test with 5 possible choices :

Getting a particular answer correct by guessing have probability = 0.2

Hence,

(d) True/ False would be easiest to pass while the test with 5 choices will be the most difficult one.

I hope this solves your doubt.

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