please help me with this question:
The compressive strength of samples of cement can be modeled by a normal distribution with a mean of 6000 kilograms per square centimeter and a standard deviation of 100 kilograms per square centimeter.
a. What is the probability that a sample’s strength is less than 6250 kg/cm2?
b. What is the probability that a sample’s strength is between 5800 and 5900 kg/cm2?
c. What strength is exceeded by 95% of the samples?

Question

please help me with this question: 
The compressive strength of samples of cement can be modeled by a normal distribution with a mean of 6000 kilograms per square centimeter and a standard deviation of 100 kilograms per square centimeter.
a.	What is the probability that a sample’s strength is less than 6250 kg/cm2?
b.	What is the probability that a sample’s strength is between 5800 and 5900 kg/cm2?
c.	What strength is exceeded by 95% of the samples?