Which measure of central tendency refers to the arithmetic average of a group of numbers or values?

When 6-month-olds listen to the words "Mommy" and "Daddy" while looking at side-by-side videos of their parents, they

A) always look longer at their mother. B) always look longer at their father. C) look longer at the video of the named parent. D) look longer at the parent who feeds them most often.

__________ is the strongest predictor of frequent, face-to-face interaction with young grandchildren

A) The quality of the parent–grandparent relationship B) Living nearby C) The age of the grandparents D) Being a paternal, rather than a maternal, grandparent