Demand per hour for gasoline at a local station is normally distributed with a mean of 860 gallons and std deviation of 55 gallons

Demand per hour for gasoline at a local station is normally distributed with a mean of 860 gallons and std deviation of 55 gallons.

What is the probability that demand is greater than 1800 gallons over a 2-hour period?

Enter your answer as a decimal value, rounded to 4 decimal places

Demand per hour for gasoline at a local station is normally distributed with a mean of 850 gallons and standard deviation of 55 gallons.

What is the probability that demand for a particular hour will be less than 900 gallons? 

Demand per hour for gasoline at a local station is normally distributed with a mean of 850 gallons and standard deviation of 25 gallons.

What is the theoretical probability that exactly 850 gallons will be sold in an hour?