**Exponential Growth and Decay -- Quiz**

**Problem 1. **
50 micrograms of radioactive iodine is injected into a patient's bloodstream at time t=0. The amount R(t) left after t days is given by the formula

.

(a) How much iodine, in micrograms, is going to be left after 3 days?

**(A) **
20.51
**(B) **
64.19
**(C) **
38.56
**(D) **
27.98

(b) Find the half-life of the iodine, in days.

**(A) **
11.5
**(B) **
6.25
**(C) **
8.00
**(D) **
12.3

**Problem 2.**
** **
A bank offers 5% annual percentage rate
compounded continuously
. That means that if your initial deposit is
, the balance on your account after t years is

.

How many years will it take for your money to double?

**(A) **
13.86
**(B) **
1.38
**(C) **
25.89
**(D) **
40.00

*MTH 111 Quizzes, B. Kaskosz and L. Pakula, 2001.*