Flight Sheremetyevo International Airport departs from Moscow Sheremetyevo International Airport at 11:50 and arrives at Riga Riga International Airport at 13:35.
The flighttime is about 4h 45m. The distance travelled ("as the bird flies"): 1498 Km. So the average speed is roughly 315 Km.
There is an 3 hour time difference between Moscow and Riga