Ken took 6 hours to travel from Country S to Country T at 55 km/h. Then he travelled from Country T to another country at 1.8 times his original speed. 30% of the distance from Country S to Country T is equal to ¹₃ of the distance from Country T to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country S to Country T
= 6 x 55
= 330 km

Speed from Country T to another country
= 1.8 x 55
= 99 km/h

30% = ³⁰₁₀₀ = ³₆

³₁₀ Distance from Country S to Country T = ¹₃ Distance from Country T to next country
³₁₀ Distance from Country S to Country T = ³₉ Distance from Country T to next country

10 u = 330
1 u = 330 ÷ 10 = 33

Distance from Country T to the next country
= 9 u
= 9 x 33
= 297 km

Time taken from Country T to the next country
= 297 ÷ 99
= 3 h

Total distance of the whole journey
= 330 + 297
= 627 km

Total time taken for the whole journey = 6 + 3 = 9 h

Average speed of the whole journey
= 627 ÷ 9
= 69 ⁶₉
= 69 ²₃ km/h

Answer(s): 69 ²₃ km/h