SOLUTION: Consider the approximately normal population of heights of male college students with mean μ = 70 inches and standard deviation of σ = 6.4 inches. A random sample of 10 h

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Question 675613: Consider the approximately normal population of heights of male college students with mean μ = 70 inches and standard deviation of σ = 6.4 inches. A random sample of 10 heights is obtained.
Find the proportion of male college students whose height is greater than 72 inches. (Give your answer correct to four decimal places.
I have worked this out several times and still get the same answer which is incorrect. HELP. Thanks
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!
 

Hi

Re: TY, might consider,  "A random sample of 10 heights is obtained" is not

what the question is in reference to.

"Find the proportion of male college students whose height is greater than 72 inches" 

P(x > 72) = 1 - P( z ≤ (72-70)/6.4) = 1 - P(z≤ .3125) = 1 - .6227 = .3773 



μ = 70  ,  σ = 6.4

Find the proportion of male college students whose height is greater than 72 inches.

SAMPLE: 10 heights 

P( x > 72) = 1 -  P(z+%3C=+%2872-70%29%2F%286.4%2Fsqrt%2810%29%29= 1 -P(z=.9882) = 1-.8385 = .1615  

TI normalcdf(z)  gives the portion of the area under the standard normal curve to the LEFT of the z-value entered.

Important to Understand z -values as they relate to the Standard Normal curve:

Below:  z = 0, z = ± 1, z= ±2 , z= ±3 are plotted.  

For ex: normalcdf(2) - normalcdf(-2) would give the portion of the area under the curve between those two z-values 

Note: z = 0 , 50% of the area under the curve is to the left and 50%  to the right