Suppose that r_t follows the model r_t = r_t1 + a_t 0.9a_t1, and we have r₁₀₀₁ = 1.2 and r₁₀₀₀ (1) = 1.0, where r_t(1) denotes the 1 step ahead prediction of r_t+1 at the forecast origin t. Compute r₁₀₀₁(1).