help on probabilities!

#1
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?