Time taken to travel first 4 km = distance/speed =4/10= 0.4 hr
Time taken to travel next 4 km = 4/20= 0.2 hr
Time taken to travel next 4 km = 4/60 = 0.067 hr
Average speed = total distance traveled/ total time taken to travel that distance
= 12/ 0.667 = 17.991 kmph or 18 kmph

With speed of 48km/hr n time 10hrs
Distance covered = 48×10=480km
person wants to cover the distance in 8 hrs
using formula
speed=distance/time= 480/8= 60km/hrs
so speed of the car should be increase by 60-48=12km/hrs in order to cover distance in 8 hrs.

COBOL stands for Common Business Oriented Language. It is imperative, procedural, and object-oriented. A compiler is a computer program that takes other computer programs written in a high-level (source) language and coverts them into another program, machine code, which the computer can understand.