Vincent took 6 hours to travel from Country X to Country Y at 65 km/h. Then he travelled from Country Y to another country at 1.8 times his original speed. 40% of the distance from Country X to Country Y is equal to ¹₆ of the distance from Country Y to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country X to Country Y
= 6 x 65
= 390 km

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

40% = ⁴⁰₁₀₀ = ²₆

²₅ Distance from Country X to Country Y = ¹₆ Distance from Country Y to next country
²₅ Distance from Country X to Country Y = ²₁₂ Distance from Country Y to next country

5 u = 390
1 u = 390 ÷ 5 = 78

Distance from Country Y to the next country
= 12 u
= 12 x 78
= 936 km

Time taken from Country Y to the next country
= 936 ÷ 117
= 8 h

Total distance of the whole journey
= 390 + 936
= 1326 km

Total time taken for the whole journey = 6 + 8 = 14 h

Average speed of the whole journey
= 1326 ÷ 14
= 94 ¹⁰₁₄
= 94 ⁵₇ km/h

Answer(s): 94 ⁵₇ km/h