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From the data set of a class, the score of a student taking a test is...

From the data set of a class, the score of a student taking a test is a random variable with mean equal to 75 and variance equals to 25. How many students would have to take the test to ensure - with probability at least 0.9 - that the class average would be within 5 of 75?

Math   Statistics-And-Probability   
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Answer #1

given data are:-

we have,

according to Chebyshev's inequality :-

hence, we have,

...........a

in ques it in given that,

............ b

compairing equation a and b we have,

the number of students need to take the test = 10

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