statistics
posted by Ashley on .
The average scuba diver can stay under water for 42 minutes with a standard deviation of 8 minutes.(show graph)
B. what is the probabilty that a diver stays under for the less than 53 minutes?
c.what is the probabilty that a diver stays under between 25 and 50?
d. what is the probabilty that a diver stays under for more than 52 mintues?
e.find the cutoff number for the middle 50% of the time a diver stays down?
f.find the top 15% of time the diver stays down?
g. find the bottom 20%of the time a diver stays down?

Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion related to the Z scores.
For eg reverse the process in the table and insert the Z value in the equation above.