What is the forecast for period 16 using the three-period weighted method? (weights are t=0.5, t-1=0.4 and t-2=0.1) a. less than or equal to 890 b. greater than 890 but less than or equal to 900 c. greater than 900 but less than or equal to 910 d. greater than 910 but less than or equal to 920 e. greater than 920?