Suppose you were to collect data for the pair of given variables in order to make a scatterplot. Determine for each variable if it is the explanatory variable or the response variable.
Variables: Minutes of homework, grade on exam

Minutes of homework: response variable
Grade on exam: both

Minutes of homework: explanatory variable
Grade on exam: response variable

Minutes of homework: response variable
Grade on exam: explanatory variable

Minutes of homework: both
Grade on exam: response variable

Minutes of homework: explanatory variable
Grade on exam: both