Unsure how to go about computing GDP for the following problem I came across this question where the GDP for the years 1995-1997 is given. Then I was asked to compute the growth rate every year which I'm aware of.The next question was to compute the average which is simple divison.However, the final question asks me to predict the GDP for the year of 2012 using the average rate of GDP between 1995-1997. I understand the tedius way to go about solving this problem is to keep computing the GDP from 1997 all the way upto 2012. Is there a simplar way I can determine the GDP of a particular year, using an average growth rate?
Generic growth formula:  

$$\frac{V_t}{V_{t_0}} = (1 + r)^{t-t_0}$$

Solving for $r$ will give you a growth rate in terms of the units of $t$ and $t_0$.  In your example, that's years.  

You currently have a growth rate and the value in 1997.  Projected value in 2012 would be 

$$V_{2012} = V_{1997} \cdot (1 + r)^{2012-1997} = V_{1997} \cdot (1 + r)^{15}$$

This assumes that $r$ is the decimal (not percentage) average growth rate that you calculated.  

I'll leave it up to you whether your original calculations of the growth rate are consistent with this method of calculating the growth rate.  If not, you may want to recalculate it.  

The formula that I gave is a generic one.  While you may be applying it to GDP, this will work for the growth rate of any variable.  That's why I used $V$ for value rather than a variable more commonly recognized as representing GDP.