Lucy takes 5.5 hours to travel between 2 cities that are 250 km apart. She travels two fifths of the distance at a rate of 90 km/hr on a highway. She drives the rest of the distance on local roads. What is her average speed for the second part of her journey?

Answer 1

distance 1st part ... 2/5 * 250 km

travel time 1st part ... (2/5 * 250 km) / 90 kph

distance 2nd part ... 250 km minus distance 1st part

time 2nd part ... 5.5 hr minus time 1st part

average speed 2nd part ... distance 2nd part divided by time 2nd part