Tim took 6 hours to travel from Country M to Country N at 50 km/h. Then he travelled from Country N to another country at 1.8 times his original speed. 60% of the distance from Country M to Country N is equal to ¹₆ of the distance from Country N to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country M to Country N
= 6 x 50
= 300 km

Speed from Country N to another country
= 1.8 x 50
= 90 km/h

60% = ⁶⁰₁₀₀ = ³₆

³₅ Distance from Country M to Country N = ¹₆ Distance from Country N to next country
³₅ Distance from Country M to Country N = ³₁₈ Distance from Country N to next country

5 u = 300
1 u = 300 ÷ 5 = 60

Distance from Country N to the next country
= 18 u
= 18 x 60
= 1080 km

Time taken from Country N to the next country
= 1080 ÷ 90
= 12 h

Total distance of the whole journey
= 300 + 1080
= 1380 km

Total time taken for the whole journey = 6 + 12 = 18 h

Average speed of the whole journey
= 1380 ÷ 18
= 76 ¹²₁₈
= 76 ²₃ km/h

Answer(s): 76 ²₃ km/h