Why do scientists look for patterns in the world?

The independent variable is the type of music.the dependent variable is the pulse rate.the intervening variable is the age of the subject.if the mother does not like rock, her pulse is likely to not increase.the same might be true for the sister.the friend may like rap and gets excited.to establish cause/effect relationship, all of the subjects must be consistent.hope i .

You would do 1500/4 and the answer is 375

Use a magnet to separate iron, evaporate water, i'm not sure how to separate the other two i'm sorry but good luck