Algebra 1b unit 4

Question

When I drive from Boise to Salt Lake City, the route I take is 364 miles long. I usually drive, on average 75 mph, but last time there was some construction which slowed me down. When I’d traveled only 1/3 of the way, I’d averaged only 63 mph. How fast would I have to drive on the second half of the trip if I want my trip to take me the normal time? 

Answer 1

1. When I drive from Boise to Salt Lake City, the route I take is 364 miles long. I usually drive, on average 75 mph, but last time there was some construction which slowed me down. When I’d traveled only 1/3 of the way, I’d averaged only 63 mph. How fast would I have to drive on the second half of the trip if I want my trip to take me the normal time? 
2. Time taken on normal drive = Distance/ Speed = 364/ 75 = 4.85333 hour
3. 1/3 rd 0f 364 = 121.333 miles covered at speed of 63 mph
4. time taken for 1/3rd = distance /speed = 121.333/63 = 1.926 hour
5. time available = 4.85333 - 1.926 = 2.927 hour
6. distance to be coved now = 364 - 121.333= 242.667 mile
7. Speed needed = Distance / time = 242.667/ 2.927 miles/hour