a researcher would like to know if lab rats prefer the taste of cherry flavor or grape flavor. to find out, she mixes some cherry kool-aid into the water bottles of 8 rats and measures how much of it each drinks in a 5-minute time period. the next day she mixes grape kool-aid into the water bottles of the same 8 rats and measures how much they drink in a 5-minute time period. what hypothesis test would be used to evaluate the data?