Is this valid? Determine whether each of the following simulation designs is valid. Justify your answer. (a) According to a recent poll, $75 \%$ of American adults regularly recycle. To simulate choosing a random sample of 100 U.S. adults and seeing how many of them recycle, roll a 4 -sided die 100 times. A result of $1,2,$ or 3 means the person recycles; a 4 means that the person doesn't recycle.
(b) An archer hits the center of the target with $60 \%$ of her shots. To simulate having her shoot 10 times, use a coin. Flip the coin once for each of the 10 shots. If it lands heads, then she hits the center of the target. If the coin lands tails, she doesn't.