Consider the approximately normal population of heights of m

Consider the approximately normal population of heights of male college students with mean = 70 inches and standard deviation of = 4.2 inches. A random sample of 12 heights is obtained.

(A). Find P(x > 69). (Give your answer correct to four decimal places.)


(B). Find P(x < 63). (Give your answer correct to four decimal places.)

**Answered the last two times this question was submitted was wrong.

Solution

Mean ( u ) =70
Standard Deviation ( sd )=4.2
Number ( n ) = 12
Normal Distribution = Z= X- u / (sd/Sqrt(n) ~ N(0,1)                  
a)
P(X > 69) = (69-70)/4.2/ Sqrt ( 12 )
= -1/1.212= -0.8248
= P ( Z >-0.8248) From Standard Normal Table
= 0.7953  
b)
P(X < 63) = (63-70)/4.2/ Sqrt ( 12 )
= -7/1.2124= -5.7735
= P ( Z <-5.7735) From Standard NOrmal Table
= 0