When \(\lg y\) is plotted against \(x\), a straight line graph passing through the points \((2.2,3.6)\) and \((3.4,6)\) is obtained.

(i) Given that \(y=Ab^x\), find the value of each of the constants \(A\) and \(b\).

(ii) Find \(x\) when \(y=900\).