Answer:
At least 75% of the exam scores fall between 72 and 96.
Step-by-step explanation:
Chebyshev Theorem
The Chebyshev Theorem can also be applied to non-normal distribution. It states that:
At least 75% of the measures are within 2 standard deviations of the mean.
At least 89% of the measures are within 3 standard deviations of the mean.
An in general terms, the percentage of measures within k standard deviations of the mean is given by [tex]100(1 - \frac{1}{k^{2}})[/tex].
Apply Chebychev's Theorem to the data using k=2.
k = 2, so within 2 standard deviations of the mean, interval in which at least 75% of the measures fall.
In this question:
Mean of 84, standard deviation of 6.
84 - 2*6 = 84 - 12 = 72
84 + 2*6 = 84 + 12 = 96
At least 75% of the exam scores fall between 72 and 96.