Agnes wanted to know which brand of gum had the longest lasting flavor. She had 5 of her friends rinse their mouths for 1
minute with water then put in a piece of gum (all peppermint
flavored). They chewed at a rate of 60 chews per minute. Then
they recorded when the gum apparead to have lost its flavor. The
friends then repeated the experiment with the remaining two
brands of gum. Trident is the least expensive of the three brands,
so that's what she chews the most.
What is the independent variable?