Carl took 5 hours to travel from Country B to Country C at 64 km/h. Then he travelled from Country C to another country at 1.5 times his original speed. 50% of the distance from Country B to Country C is equal to ¹₆ of the distance from Country C to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country B to Country C
= 5 x 64
= 320 km

Speed from Country C to another country
= 1.5 x 64
= 96 km/h

50% = ⁵⁰₁₀₀ = ¹₅

¹₂ Distance from Country B to Country C = ¹₆ Distance from Country C to next country
¹₂ Distance from Country B to Country C = ¹₆ Distance from Country C to next country

2 u = 320
1 u = 320 ÷ 2 = 160

Distance from Country C to the next country
= 6 u
= 6 x 160
= 960 km

Time taken from Country C to the next country
= 960 ÷ 96
= 10 h

Total distance of the whole journey
= 320 + 960
= 1280 km

Total time taken for the whole journey = 5 + 10 = 15 h

Average speed of the whole journey
= 1280 ÷ 15
= 85 ⁵₁₅
= 85 ¹₃ km/h

Answer(s): 85 ¹₃ km/h