1. A sample of radium has a weight of 1.5 mg and a half-life of approximately 6 years. Find a function f which models the amount of radium f(t), in mg, remaining after t years.

use an equation of ratios to determine the amount of gas needed to fill the tank.

    0.2             0.8

  =    

288.75             x

                                                              231 gal

so, 0.2x = (0.8)(288.75 gal), and x = = 1155 gal.

                                                                0.2

it would take 1155 gal. to fill the tank.

the cost would be

1155 gal         $3

* = $3465   (answer)

      1           1 gal

hope this you

the square root of what number? if you add that, then someone will probably answer the question.