Assume that the random variable XX is normally distributed, with mean = 50 and standard deviation = 7. How would I compute the probability P( X > 35 )P(X>35)?

1 Answer
May 9, 2017

P(Z> -2.14)=0.9838P(Z>2.14)=0.9838

Explanation:

X~N(50,7^2)X~N(50,72)

P(X>35)P(X>35)

standardising

P(X>35)rarrP(Z>(35-50)/7)P(X>35)P(Z>35507)

=P(Z> -2.14)" ( 2dps)=P(Z>2.14)(2dps)

now by the symmetry of the Normal curve

P(Z> -2.14)=P(Z<2.14)P(Z>2.14)=P(Z<2.14)

so we now look up directly from tables

P(Z> -2.14)=0.9838P(Z>2.14)=0.9838