For what values of a and b is x^64 +ax^b+25 a perfect square for all integer values of x?

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?

21 a stick 7 inches long is broken into two pieces, so that one piece is twice as long as the other one. how long are the two pieces?

Sam opened a money-market account that pays 3% simple interest. he started the account with $7,000 and made no further deposits. when he closed the account, he had earned $420 in interest. how long did he keep his account open?