A guy bikes 15 miles in 1 hour, then rests for an hour. Then he bikes 25 in 2 hours. What was his average speed for the trip?

He went 15 miles/hour in the first sequence, and then 12.5 miles/hour (25 miles/2 hours) in the second sequence. If you take into account the hour he rested between segments: 15 miles/hour, 0 miles/hour, and 12.5 miles/hour. So (15+0+12.5)/3 = 9.17 miles/hour is his average. However, if you are not taking into account the whole trip, and only the time he was biking: (15+12.5)/2 = 13.75 miles/hour

answer : haversian

[explanation: -(compact bone is organized as parallel columns, known as haversian systems, which run lengthwise down the axis of long bones. these columns are composed of lamellae, concentric rings of bone, surrounding a central channel, or haversian canal, that contains the nerves, blood vessels, and lymphatic system of the bone)]