John attained a score of 65 on his stats exam The mean for t

John attained a score of 65 on his stats exam. The mean for the class was a 70 with a SD of 10. What percentage of students scored below and above John?

a.31 and 69

b.40 and 60

c.45 and 55

d.10 and 90

Solution

P( X < 65)

= P(Z < (65 - 70)/10))

= P(Z < -0.5)

= 0.3085

Lower percentage = 31%

P(X > 65) = P(Z > -0.5) = 0.6915

UUpper percentage = 69.15%

Therefore, 31 and 69.

=