Xavier took 5 hours to travel from Country Y to Country Z at 60 km/h. Then he travelled from Country Z to another country at 1.5 times his original speed. 40% of the distance from Country Y to Country Z is equal to ¹₃ of the distance from Country Z to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country Y to Country Z
= 5 x 60
= 300 km

Speed from Country Z to another country
= 1.5 x 60
= 90 km/h

40% = ⁴⁰₁₀₀ = ²₅

²₅ Distance from Country Y to Country Z = ¹₃ Distance from Country Z to next country
²₅ Distance from Country Y to Country Z = ²₆ Distance from Country Z to next country

5 u = 300
1 u = 300 ÷ 5 = 60

Distance from Country Z to the next country
= 6 u
= 6 x 60
= 360 km

Time taken from Country Z to the next country
= 360 ÷ 90
= 4 h

Total distance of the whole journey
= 300 + 360
= 660 km

Total time taken for the whole journey = 5 + 4 = 9 h

Average speed of the whole journey
= 660 ÷ 9
= 73 ³₉
= 73 ¹₃ km/h

Answer(s): 73 ¹₃ km/h