Question

In an achievement test, the mean score of normally distributed values is 70 and the standard deviation is 12. What is the percentage of students who got a score of 85 and above?

Answer 1

$$P(X\ge85)=1-P(X<85)$$

$$=1-P(Z<\dfrac{85-70}{12})=1-P(Z<1.25)$$

$$\approx0.10565$$

$10.565\%$