The half-life of strontium-90 is 28 years. Suppose we have a 52 mg sample.
(a) Find a function that models the mass m(t) remaining after t years.
m(t) =
(b) How much of the sample will remain after 60 years?
m(60) =
mg.
(c) How long will it take the sample to decay to a mass of 13 mg?
Your answer is
years.

Amountain climber starts a climb at an elevation of 453 feet above sea level at his first rest stop he has climbed 162 feet and by his second rest stop he has climbed another 207 feet its getting late in the day so the climber starts his way down if the climber desends 285 feet how much does he need to ascend or descend to return to the original starting point