Solve for X $\mathrm { A } = \mathrm { Ce } \mathrm { e } ^ { - 0.1813 \mathrm { t } }$

question 68

Multiple Choice

Solve for x.
-The radioactive decay of radon 222 can be described by the equation $\mathrm { A } = \mathrm { Ce } \mathrm { e } ^ { - 0.1813 \mathrm { t } }$ , where $\mathrm { C }$ is the original amount of radon and $\mathrm { A }$ is the amount of radon after $\mathrm { t }$ days. If $2.5$ milligrams are in a laboratory container today, how much was there is the container 11 days ago? Round to the nearest hundredth.

• A) \(2.84 \mathrm { mg }\)
• B) \(0.34 \mathrm { mg }\)
• C) \(45.68 \mathrm { mg }\)
• D) \(18.37 \mathrm { mg }\)

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