In: Statistics and Probability
Data given:
Mean = 77, SD = 4, P(Y > 70) = ?;
P(Y > 70) = P(Y - mean > 70 - mean)
= P( (Y - mean)/SD > (70 - mean)/SD
= P(Z > (70 - mean)/SD)
= P(Z > (70 - 77)/4)
= P(Z > -1.75)
= 1 - P(Z <= -1.75)
= 0.96----------------from normal distribution
table.
Approximately 96% students scored above her.