Answer :
The number of students who scored less than 60 or more than 80 is atmost 9.
What is mean and variance?
A measurement of central dispersion is the mean and variance.
The average of a group of numbers is known as the mean.
The variance is calculated as the square root of the variance.
Chebyshev's rule is applicable for any distribution. If distribution is a normal distribution, then we can use empirical rule.
step: 2
Given mean is 70 and variance is 25.
We know standard deviation is square root of variance. So
σ = SD =√25
= 5
So the standard deviation is 5.
Here
60=70−2×5
80=70+2×5
So between 60 and 80 is within 2 standard deviation about mean.
So at least 75% are between 60 and 80.
Then percentage outside this is at most 25%.
Outside this means less than 60 more than 80.
So at most 25% of total data are less than 60 more than 80.
We have total 35 students.
25% of 35 students = 0.25*35
= 8.75
number of students who scored less than 60 or more than 80 is atmost 9
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