Last year there were 15 porcelain dolls in lanny's collection, after trading for a rare doll, she now has 12 dolls. what is the percent decrease of her collection?

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Find the distance between the pair of points a(-1,8) and b(-8,4)

Atest consists of 10 multiple choice questions, each with 5 possible answers, one of which is correct. to pass the test a student must get 60% or better on the test. if a student randomly guesses, what is the probability that the student will pass the test?