The owner of a pizza parlor called every fifth person who ordered pizza last week to rate the pizza. What type of statistical study is this

I like noodles in a cup and I eat it with a fork

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.