List of top Quantitative Ability Questions on Geometric Progression asked in XAT

If \(X=\dfrac{a}{1+r}+\dfrac{a}{(1+r)^2}+\cdots+\dfrac{a}{(1+r)^n}\), then what is the value of \(a+a(1+r)+a(1+r)^2+\cdots+a(1+r)^{n-1}\)?