Statistics help!! Thanks!!!?

Problem 19)


Researchers at a pharmaceutical company have found that the effective time duration of a safe dosage of a pain relief drug is normally distributed with mean 2 hours and standard deviation 0.3 hour. For a patient selected at random:


a) What is the probability that the drug will be effective for 2 hours or less?


b) What is the probability that the drug will be effective for 1 hour or less?


c) What is the probability that the drug will be effective for 3 hours or more?

Statistics help!! Thanks!!!?
a is 50% since 2 is the mean


b is 3 1/3 standard deviations below the mean and c is 3 1/3 above. They will each have the same probability which you can look up in a normal probability chart (look up 3.33 then subtract from 0.5000)
Reply:a) If the mean is two hours, then there is a 50% or 1/2 chance that the drug will be effective for 2 hours or less.





b) I'll assume that your .3 is 1/3 hour or 20 min. One hour would be 3 standard deviations from the mean, where .15% of occurences are. So, .15/100 or 15/10000 or 3/2000 chance.





c) The exact same as b) where you are three standard devations from the mean. 3/2000