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Justin now has a final exam today. There are 20 questions with 3 options. Each
question only has one correct answer. He just needs to make a 75 to pass the class
(meaning he needs to get 15 right). What is the probability of him doing so?

Sagot :

Answer: .0142%

Step-by-step explanation:

MrRoyalidn

The probability that Justin passes his final exam is 0.0147%

How to determine the probability?

The given parameters are:

  • Questions, n = 20
  • Pass mark, x = 25
  • Number of options = 3

Only one of the options can be correct.

So, the probability that he answers a question correctly is:

p = 1/3

To get a pass mark of 75, he must score at least 15.

So, the probability is represented using:

P(x >= 15) = P(15) + P(16) + ..... + P(20)

Each probability is calculated using:

[tex]P(x) = ^nC_r * p^x *(1 -p)^{n - x}[/tex]

Using the above formula, we have:

P(15) = 0.00012546624

P(16) = 0.0000193115

P(17) = 0.00000223803

P(18) < 0.000001

P(19) < 0.000001

P(20) < 0.000001

When the above probabilities are added, we have:

P(x >= 15) = 0.00014720925

Express as percentage

P(x >= 15) = 0.014720925%

Approximate

P(x >= 15) = 0.0147%

Hence, the probability that Justin passes is 0.0147%

Read more about probability at:

https://brainly.com/question/251701

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