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crimeas [40]
1 year ago
11

第 5 个问题 a multiple choice exam has 10 questions. each question has 3 possible answers, of which one is correct. a student knows

the correct answers to 4 questions and guesses the answers to the other 6 questions. it turns out that the student answered the first question correctly. what are the chances that the student was merely guessing?
Mathematics
1 answer:
tatuchka [14]1 year ago
8 0

The chances that the student was merely guessing is 1/3.

Bayes Theorem determines the conditional probability of an event A given that event B has already occurred.

denoted by

P(A/B)=\frac{P(A)*P(B/A)}{P(B)}

let A be the  event that the student knows the answer .

B be  the  event that the student does not knows the answer .

and

E be the event he gets answer correct .

According to the given question

P(A)=\frac{4}{10} \\\\ P(B)=1-\frac{4}{10} =\frac{6}{10}

Probability that the answer is correct ,given that he knows the answer is

P(E/A)=1

Probability that the answer is correct ,given that he guesses it is

P(E/B)=\frac{1}{3}   [as the MCQ has 3 options and only one is correct]

We need to find the probability that he guesses the answer given that it is correct.

Required probability P(B/E)=\frac{P(B)*P(E/B)}{P(A)*P(E/A)+P(B)*P(E/B)}

Substituting the values we get

P(B/E)=\frac{\frac{6}{10} *\frac{1}{3} }{\frac{4}{10} *1+\frac{6}{10} *\frac{1}{3} }

=\frac{6}{30}*\frac{30}{18}  \\ \\ =\frac{6}{18} \\ \\ =\frac{1}{3}

Therefore ,  the chances that the student was merely guessing is 1/3.

Learn more about Probability here brainly.com/question/13140147

#SPJ4

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I'll attach a photo of my answers. I can also provide work if needed, but based on this photo, it looks like an online quiz so I won't waste my time with that.

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zubka84 [21]

The measures of central tendency for this data set are as follows:

  1. Mean = 3.55.
  2. Median = 3.5.
  3. Mode = 3.

<h3>How to calculate measures of central tendency?</h3>

In Mathematics, there are three (3) main measures of central tendency and these include the following:

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For the mean, we have:

Mathematically, the mean for this data set would be calculated by using this formula:

Mean = [F(x)]/n

For the total number of data, we have:

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Substituting the parameters into the formula, we have:

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For the median, we have:

First of all, we would order the data from lowest to highest and then determine the median as follows:

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A mode refers to the most frequently occurring number in a data set. Thus, the mode for this data set is equal to 3.

In conclusion, a box plot of the measures of central tendency for this data set is shown in the image attached below.

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