When Teen Talk Barbie uttered those immortal words "Math class is tough!" in 1992 the American Association of University Women criticized this so strongly that Mattel deleted the phrase from the doll's vocabulary and offered a swap to anyone who had such a doll. Each doll was programmed to say 4 different phrases randomly selected from a list of 270 phrases such as "Will we ever have enough clothes?", "I love shopping!", and "Wanna have a pizza party?" What percentage of the dolls manufactured at that time uttered the offending phrase about math class?