To find the value of $y$ when $x = 5$ using an exponential curve of best fit, we need to follow these steps:

1. Identify the exponential form: The general form of an exponential function is: $y = ab^x$ where:

   • $a$ is the initial value (when $x = 0$),
   • $b$ is the base (the rate of growth or decay).

2. Determine the parameters $a$ and $b$: You need to fit the data to the exponential curve to determine the values of $a$ and $b$. This can be done using statistical methods like regression analysis or logarithmic transformation (if you are doing this by hand or using software).

3. Substitute $x = 5$ into the equation: Once we have the values of $a$ and $b$, substitute $x = 5$ into the equation to find $y$.

Could you provide the data set mentioned in the table so I can assist you in finding the values of $a$ and $b$?