Question

Mean of 75 and SD of 6.38 1. What is the probability of a raw score falling between raw scores of 65 and 78?
The two Z scores to use-->
Two areas under normal curve to use-->
Probabilty of score falling between 65 and 78-->

Answer 1

Solution :

Given that ,

mean = = 75

standard deviation = = 6.38

1)

P(65 < x < 78) = P((65 - 75 / 6.38) < (x - ) / < (78 - 75 ) / 6.38) )

P(65 < x < 78) = P(-1.5674 < z < 0.4702)

P(65 < x < 78) = P(z < 0.4702) - P(z < -1.5674)

P(65 < x < 78)  = 0.6809 - 0.0585 = 0.6224

Probability = 0.6224