a sample of a radioactive isotope had an initial mass of 490 mg in the year 1996 and decays exponentially over time. a measurement in the year 1998 found that the sample's mass had decayed to 240 mg. what would be the expected mass of the sample in the year 2005, to the nearest whole number?

Abox contains 1 plain pencil and 4 pens. a second box contains 5 color pencils and 5 crayons. one item from each box is chosen at random. what is the probability that a plain pencil from the first box and a color pencil from the second box are selected? write your answer as a fraction in simplest form.

Suzanne began a trip with 18 1/2 gallons of gas in the gas tank of her car if she hughes 17 3/4 gallons on the trip how many gallons does she have left once she finish the trip

If a is a nonzero real number then the reciprocal of a is