Question

in an objective exam which has 3 answer options each for all the 20 Questions.what is the probability that Same answers 9 questions incorrectl​

Answer 1

Answer:

18 is the answer

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Answer 2

Concept:

Probability defines that the how likely something is to happen. The outcomes are equally likely outcomes that shows that all the outcomes have the same probability.

Given:

There are 3 answer options each for all the 20 questions.

Find:

The probability of getting 9 questions incorrect.

Solution:

As the question has 3 answer options, only one correct option and two incorrect options and all the outcomes are equally likely outcomes.

Probability of getting the correct answer of the question, q = 1/3

Similarly, Probability of getting the incorrect answer of the question, p = 2/3

Probability of getting the 9 questions incorrect,

P = ⁿₓC  pˣ q⁽ⁿ⁻ˣ⁾

Here, 9 question are incorrect from 20 questions. So, n=20 and x=9,

Solving the binomial probability,

P = ²⁰₉C  [2/3]⁹[1/3]⁽²⁰⁻⁹⁾

P= 0.0247

Hence, the probability of getting 9 incorrect questions is  0.0247.

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