A Researcher Records the Sound (In Decibels)during a Series of Lessons

Multiple Choice

A researcher records the sound (in decibels) during a series of lessons taught by a substitute teacher at a local elementary school.In his study,he found that the sound was 80±6 (M±SD) decibels.Assuming the data are normally distributed,which of the following is an appropriate conclusion?

A) 68% of classes were between 68 and 80 decibels.
B) 5% of classes were louder than 68 decibels.
C) 95% of classes were between 68 and 92 decibels.
D) all of the above