The random variable X is normally distributed with mean μ=30 and standard deviation σ =10. Use the transformation [tex] \frac{X-\mu}{\sigma} [/tex] for calculating the probability. This value is called Z-score.
The Z score is [tex] Z=\frac{40-30}{10} =1 [/tex].
Refer to the standard normal distribution table.
The probability
[tex] P(X>40)=P(Z>1)=1-P(Z<1)=0.16
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