99.7% of students in a class of 100 weigh between 60 kg and 96 kg. Assuming the data is normally distributed, what are the mean and the standard deviation?
A. |
µ = 78kg; σ = 18kg |
|
B. |
µ = 78kg; σ = 9kg |
|
C. |
µ = 78kg; σ = 18kg |
|
D. |
µ = 78kg; σ = 6kg |
Solution :
Using Empirical rule,
P( - 3< X < + 3) = 99.7%
P(78 - 3 * 6 < X < 78 + 3 * 6) = 99.7%
P(60 < X < 96) = 99.7%
µ = 78 kg; σ = 6 kg
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