Spot speed study was carried out to redesign the stretch of major district road. The data collected during the study is given below. Speed Range Frequency of Vehicles kmph Two Wheelers Cars Others 0-10 5 0 0 10-20 20 6 4 20-30 24 12 4 30-40 20 30 5 40-50 30 60 30 50-60 35 35 30 60-70 25 35 15 70-80 10 15 10 80-90 10 18 2 90-100 1 6 0 (i) What is the design speed for redesigning existing MDR? (ii) (iii) What are upper and lower speed limits for mixed traffic? What are the different measures to increase the spot speed of vehicles moving on the road? (iv) Check whether the speed distribution is reasonably normal or not.