# statistic

posted by on .

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 μ  19.8 minutes with a
standard deviation of   7.2 minutes. Assuming that
the distribution is approximately normal, find each of
the following probabilities.
a. What is the probability of randomly selecting
a student with a treadmill time greater than
25 minutes? In symbols, p(X  25)  ?
b. What is the probability of randomly selecting a
student with a time greater than 30 minutes? In
symbols, p(X  30)  ?
c. If the school required a minimum time of 10 minutes
for students to pass the physical education course,
what proportion of the freshmen would fail?

• statistic - ,

a. Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability related to the Z score.

b, c. Same process.