Zane took 6 hours to travel from Country Y to Country Z at 65 km/h. Then he travelled from Country Z to another country at 1.8 times his original speed. 70% of the distance from Country Y to Country Z is equal to ¹₆ 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
= 6 x 65
= 390 km

Speed from Country Z to another country
= 1.8 x 65
= 117 km/h

70% = ⁷⁰₁₀₀ = ⁷₆

⁷₁₀ Distance from Country Y to Country Z = ¹₆ Distance from Country Z to next country
⁷₁₀ Distance from Country Y to Country Z = ⁷₄₂ Distance from Country Z to next country

10 u = 390
1 u = 390 ÷ 10 = 39

Distance from Country Z to the next country
= 42 u
= 42 x 39
= 1638 km

Time taken from Country Z to the next country
= 1638 ÷ 117
= 14 h

Total distance of the whole journey
= 390 + 1638
= 2028 km

Total time taken for the whole journey = 6 + 14 = 20 h

Average speed of the whole journey
= 2028 ÷ 20
= 101 ⁸₂₀
= 101 ²₅ km/h

Answer(s): 101 ²₅ km/h