Time left 0:58:13 A seasonal index for a monthly series is about to be calculated on the basis of three years' accumulation of data. The three previous July values were 110, 150, and 130. The average over all months is 190. The approximate seasonal index for July is O a. 1.462 O b. 3 O c. 2.462 O d. 0.684 O e. 0.487