Assume that the amount of time eighth-graders take to complete an assessment examination is normally distributed with mean of 78 minutes and a standard deviation of 12 minutes.
What proportion of eighth-graders complete the assessment examination in 72 minutes or less?
What proportion of eighth-graders complete the assessment examination in 82 minutes or more?
What proportion of eighth-graders complete the assessment examination between 72 and 82 minutes?
For what number of minutes would 90% of all eighth-graders complete the assessment examination?
