A physical fitness association is including the mile run in its secondary-school fitness test

for boys. The time for this event for boys in secondary school is normally distributed
with a mean of 450 seconds and a standard deviation of 40 seconds. If the association
wants to designate the fastest 10% as excellent, what time should the association set for
this criterion?

1 answer

Z = (score-mean)/SD

Look in the back of your statistics textbook for a table called something like “area under normal distribution” to find the proportion/probability (.10) in the smaller portion and its Z score. Insert data into above equation and solve for score.