Question

Scores obtained by students in an advanced placement test has a mound shaped (normal)distribution with a mean of 70 and a standard deviation of 10. the approximate proportion of students whose scores are above 90 points is close to

Answer 1

To evaluate the proportion of students who scored over 90 points will evaluated as follows:
P(x>20)=1-P(z<Z)
where:
z=(x-μ)/σ
where:
x=90
μ=70
σ=10
z=(90-70)/10
z=2
P(z<2)=0.9772
hence
P(x>90)=1-0.9772=0.0228