# A specific substance follows a continuous exponential decay model. It has a half-life of 5 days.?

Help me with this question please. much appreciated!!

Question: A specific substance follows a continuous exponential decay model. It has a half-life of 5 days. At the start of the expriment, 365.8 g is present.

a) Let t be the time (in days) since the start of the expriment, and let y be the amount of the substance at the time t.

Write a formula relation y to t.

b) how much will be present in 21 days?

Thank you!

### 1 Answer

Relevance

- MichaelLv 73 weeks ago
a) Let t be the time (in days) since the start of the experiment,

and let y be the amount of the substance at the time t.

Write a formula relation y to t.

y = 365.8(1/2)^(t/5) <–––––

b) how much will be present in 21 days?

y = 365.8(1/2)^(21/5)

y = 19.903

19.9 g <–––––

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