Recall that an exponential function, with the $x$-axis as an asymptote, can be expressed as $y = a \cdot m^x$ where $a$ is the initial value and $m$ is the multiplier. Find the initial value, the multiplier, and the time units in each of the following situations.  

1. Bread costs $\$1.87$ now and is increasing in price by $2\%$ each month.

   Answer (a):

   Initial value $=\$1.87$, multiplier $=1+0.02=1.02$ , time is in months.

2. A car is worth $\$12000$ now and is depreciating in value by $12\%$ each year.

   Hint (b):

   Multiplier will be down $0.12$ from $1.0$.

3. Bacteria grow at a rate of $30\%$ every hour. There are currently $1000$.

4. A $\$5000$ investment earns $1\%$ interest every month.