The radioactive substance strontium-90 has a half-life of 28 years. In other words, it takes 28 years for half of a given quantity of strontium-90 to decay to a non-radioactive substance. The amount of radioactive strontium-90 still present after t years is modeled by the expression 80*2^t/28 grams. Evaluate the expression for t = 0, t = 28 and t = 56. What does each value of the expression represent?

Question

Mathematics

Oswaldo Fitzpatrick

17 December, 13:08

The radioactive substance strontium-90 has a half-life of 28 years. In other words, it takes 28 years for half of a given quantity of strontium-90 to decay to a non-radioactive substance. The amount of radioactive strontium-90 still present after t years is modeled by the expression 80*2^t/28 grams. Evaluate the expression for t = 0, t = 28 and t = 56. What does each value of the expression represent?

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Angie Bonilla · Answer 1

80 * 2^0 = 80*1 = 80g (amount initially)

80 * 1/2 = 40 g (amount remaining after one half life)

80 * (1/2) ^2 = 80 * 1/4 = 20 g (amount remaining after 2 half lives).