Answer:
644.982
Explanation:
Given, Speed of Driver A = 145.155
Speed of Driver B = 145.827
Speed of Driver C = 1144.809
Thus, the Speed of Driver D is between 145.155 and 1144.809
It can be any value between 145.155 and 1144.809
Further, the exact middle value between 145.155 and 1144.809 is 644.982