Answer:
3.5 m/s
Step-by-step explanation
Remove brackets
d = t^2 + 0.2t + 3.3t + .66              
Combine
d = t^2 + 3.5t + .66
The initial velocity  is 3.5
 
        
             
        
        
        
Volume of a sphere is given by the formula: 

If we pull the 4 out front we have, 

.
Volume of a cone is given by the formula: 

Notice that if the height of the cone is equal to the radius, 

then it's exactly what we see in our volume formula without the 4!
 
        
        
        
Answer:
The eastbound train travels at 92 mph and the westbound train travels at 96 mph.
Step-by-step explanation:
We know that Velocity = distance / time
If the eastbound train travels at x miles per hour, the westbound train travels at x + 4 mph.
After 3.5 hours, they are 658 miles apart. If we solve for distance the formula given above we have: Distance = velocity x time. We have that the total distance between both trains is 658 miles.
Substituting the values of the problem and solving for x we have

Thus, the eastbound train travels at 92 mph and the westbound train travels at 96 mph.