Hurry ! between 1900 and 2010, how did the world’s population change? a. it increased from about 1.5 billion to almost 7 billion. b. it decreased from about 7 billion to about 1 billion. c. it increased from about 5 billion to about 7 billion. d. it decreased from about 7 billion to about 1.5 billion.
Martha participates in a research study in order to receive extra credit for her psychology class. when she arrives in the research office she is given a can of what looks and tastes like beer, but which actually contains no alcohol. in the adjoining room martha's classmate karen is also participating in the study. karen receives a can of alcoholic beer. if the experiment was designed to test the effects of alcohol on concentration, then who is exposed to the independent variable?