Question 1156208
Over the past 10 years, the local school district has measured physical fitness for all high school freshmen. During that time, the average score on a treadmill endurance task has been = 19.8 minutes with a standard deviation of = 7.2 minutes. What proportion of students have a treadmill time less than 30 minutes?
 
1st::  Find the z-score of 30
z(30) = (30-19.8)/7.2 = 1.417
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2nd:: Find the area under the normal curve below z = 1.417
Ans:: P(z<1.417) = normalcdf(-100,1.417) = 0.92
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Cheers,
Stanbon