Question

Let x have a normal distribution with mean µ = 30 and standard deviation σ = 10. calculate p(x > 40), and round your answer to two decimal places.

Answer 1

The random variable X is normally distributed with mean μ=30 and standard deviation σ =10. Use the transformation $\frac{X-\mu}{\sigma}$ for calculating the probability. This value is called Z-score.

The Z score is $Z=\frac{40-30}{10} =1$.

Refer to the standard normal distribution table.

The probability

$P(X>40)=P(Z>1)=1-P(Z$