<span>So we need to find the average speed of the bus that travels 20 km in 30 minutes. Average speed is defined as: Average speed=distance travelled/time taken or: v=s/t. We know s=20 km and t=30 minutes=0.5h. So after we input our numbers in the equation, we get: v=20km/0.5h=40km/h. So the correct answer is C) 40km/h.</span>
Answer:
"B A C" 16x20=320
Step-by-step explanation:
Answer:

Step-by-step explanation:
Circumference of the column 
Circumference of a circle
Therefore:

Area of a Circle 
Since radius of the cross section of the column =9 meters
Area of the cross section of the column
