To find out who arrived home earlier, we can calculate the time it took each person to travel the given distance.
a) Time taken by Alexandra to travel 14 km at an average speed of 20 km/h = Distance ÷ Speed = 14/20 = 0.7 hours
Time taken by Rhiannon to travel 10 km at an average speed of 24 km/h = Distance ÷ Speed = 10/24 = 0.4167 hours
Since Rhiannon took less time to travel the same distance, she arrived home earlier than Alexandra.
b) To find out how much earlier Rhiannon arrived at home, we can subtract her travel time from Alexandra's travel time:
0.7 - 0.4167 = 0.2833 hours
Therefore, Rhiannon arrived home 0.2833 hours (or approximately 17 minutes) earlier than Alexandra.