An automotive battery manufacturer wants to study the reserv…

An automotive battery manufacturer wants to study the reserve capacity of a battery (using hours).  A researcher collected a random sample of 200 batteries and recorded the corresponding number of hours each battery lasted.  Which of the following is the observational unit?

A group of boys is randomly divided into two groups. One gro…

A group of boys is randomly divided into two groups. One group watches violent cartoons for one hour, and the other group watches cartoons without violence for one hour.  The boys are then observed to see how many violent actions they take in the next two hours, and the two groups are compared.  Classify this is as: