Normal Distributions

The shelf life of a particular dairy product is normally distributed with a mean of 12 days and a variance of 9 days².

About what the probability of the products last between 12 and 15 days? Remember: $$\sigma^2:\ Variance\ \ \rightarrow\ \sigma=\sqrt[]{\sigma^2}$$

On the math portion of the SAT, scores are roughly normal, with a mean of 500 and a standard deviation of 100. What percent of scores are above 400?

Mean number of accidents a week: 6.4, Standard deviation: 1.5. What proportion of weeks have more than 7 accidents?

A grading scale is set up for 1000 students' test scores. It is assumed the scores are normally distributed with a mean score of 75 and a standard deviation of 15. How many students will have a score between 45 and 75?

What shape is a normal distribution curve?

Given a mean of 75 and a standard deviation of 7, how many students out of 500 would score higher than 68?

What's the probability x < 13? (Mean = 10, Variance = 4)

What is the area under the curve to the left of z = 0.55?

What is the area under the curve between z = 0 and z = 1.45?

What percentage of customers will spend less than $3.00 on concessions if the spending distribution is approximately normally distributed with a mean of $4.11 and a variance of $²4?