Explain simply why 180 is the correct answer to: In a car racing competition, Skye drove a 6-kilometer track. For the first 3 kilometers, his speed was 150 kilometers per hour. For the next 2 kilometers, his speed was 50 kilometers per hour more. For the remaining 1 kilometer, his speed was twice as fast as his speed on the first 3 kilometers. What is Skye's average speed for the entire race?. Explanation:
Since time is obtained by dividing distance and speed, then Skye took 3 km / 150 km per hr. = 1 / 50 of an hour to finish the first 3 kilometers of the race. His speed on the next 2 kilometers was 150 + 50 = 200 kilometers per hour. Hence, it took him 2 km / 200 km per hr. = 1 / 100 of an hour to finish the next 2 kilometers. His speed on the remaining 1 kilometer is 150 x 2 = 300 kilometers per hour. Hence, it took him 1 / 300 of an hour to finish the 1 kilometer. So, the total time it took for Skye to complete the race was 1 / 50 + 1 / 100 + 1 / 300 = 1 / 30 of an hour. Therefore, his average speed for the entire race was 6 km / 1 / 30 hour = 180 kilometers per hour.