Although Dominick's Psychology Class Is Sometimes Longer or Shorter Than

Multiple Choice

Although Dominick's psychology class is sometimes longer or shorter than usual,on average each class is 50 minutes.If the lengths of these classes form a normal curve,which statistic would enable Dominick to estimate the probability that any single class will last somewhere between 47 and 53 minutes?

A) range
B) median
C) correlation coefficient
D) standard deviation