What is the definition of sin

What is the number 321,000,000 in scientific notation? also what is the number? ?

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?

Write the expression as a single natural logarithm. 2 in a - 4 in y