To convert the annual appreciation of 10% to a monthly appreciation, we need to find the equivalent monthly growth rate.
The formula for the annual growth when compounded monthly can be derived from:
\[ (1 + r)^n = 1 + R \] where:
- \( R \) is the annual growth rate (0.10 for 10%),
- \( n \) is the number of compounding periods per year (12 for months),
- \( r \) is the monthly growth rate.
Setting it up, we get:
\[ (1 + r)^{12} = 1.10 \]
To find \( r \), we can solve for \( r \):
\[ 1 + r = (1.10)^{1/12} \]
Subtracting 1 gives us the monthly growth rate:
\[ r = (1.10)^{1/12} - 1 \]
Calculating this value, we find that:
\[ r \approx 0.00797414 \]
Thus, our monthly growth rate can be approximated as:
\[ 1 + r \approx 1.008 \]
So, the expression for monthly appreciation, t being measured in months, becomes:
\[ y = 200000 \cdot (1.008)^t \]
Therefore, the correct option representing the monthly appreciation is:
A: \( y = 200000 \cdot (1.008)^t \)