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nadezda [96]
3 years ago
9

A test consists of 100 multiple choice questions, each with five possible answers, only one of which is correct. Find the mean a

nd the standard deviation of the number of correct answers. mean: 20; standard deviation: 4 mean: 20; standard deviation: 4.47 mean: 50; standard deviation: 7.70 mean: 50; standard deviation: 4
Mathematics
1 answer:
TEA [102]3 years ago
6 0

Answer:  Mean = 20 and standard deviation = 4

Step-by-step explanation:

Let x represents the success of getting the correct answer.

Here, the total number of trials(n) = 100

The probability of getting the correct answer, p = 1/5

Thus, the mean of the number of correct answer,

\mu_x= np

\mu_x= 100\times 1/5

\mu_x= 20

Now, the standard deviation, \sigma_x= \sqrt{n\times p\times (1-p)}

\sigma_x= \sqrt{100\times 1/5\times 4/5}

\sigma_x= \sqrt{16}

\sigma_x= 4

Thus, First option is correct.



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<h3>What is the probability  about?</h3>

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