Sarah has decided that she never wants to go into debt. Therefore, she only uses her debit card and cash for purchases. The store where she is planning to purchase a dining
room set charges a 15% annual interest rate for all store credit card purchases. If Sarah
saves up the cash and uses her debit card to purchase her new $1,200 dining room set,
how much will she have to pay in interest?

Because of the violent nature of the sport, professional american football players are at risk of suffering concussions (or brain injuries) during the violent collisions that occur between players during the game. violent collisions involving hits to the head are particularly risky. suppose the commissioner of the national football league (nfl) institutes a rule requiring players to wear a new, lighter helmet that is designed to reduce head trauma during collisions between players on the field. while the new helmets the probability of a concussion resulting from each individual collision, at the same time the new helmets could also give football players an incentive to play more , which could potentially the amount of violent collisions and thus the number of concussions suffered by nfl players, all else equal.