Data help! Basic Probability!

1) The weekly demand for laser printer cartridges at Office Oasis is normally distributed with a mean of 350 cartridges and a standard deviation of 10 cartridges. There store has a policy of avoiding stockouts (having no product on hand). The manager decides that she wants the chance of a stockout in any given week to be at max 5%. How many cartridges should the store carry each week to meet this policy?

a: 367

2) On a certain section of highway, 90 percent of the motorists drive speeds greater than 100km/h and only 5 percent of the motorists drive at speeds less than 95km/h. if the speeds are assumed normally distributed,

a) determine the motorists mean driving speed and standard deviation.

b) determine the percentage of motorists that drive at speeds greater than 120 or less( last part is cut off!)

a) mean = 121.67; sd = 16.67 b) 53.9%