Mark took 6 hours to travel from Country A to Country B at 50 km/h. Then he travelled from Country B to another country at 1.5 times his original speed. 50% of the distance from Country A to Country B is equal to ¹₄ of the distance from Country B to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country A to Country B
= 6 x 50
= 300 km

Speed from Country B to another country
= 1.5 x 50
= 75 km/h

50% = ⁵⁰₁₀₀ = ¹₆

¹₂ Distance from Country A to Country B = ¹₄ Distance from Country B to next country
¹₂ Distance from Country A to Country B = ¹₄ Distance from Country B to next country

2 u = 300
1 u = 300 ÷ 2 = 150

Distance from Country B to the next country
= 4 u
= 4 x 150
= 600 km

Time taken from Country B to the next country
= 600 ÷ 75
= 8 h

Total distance of the whole journey
= 300 + 600
= 900 km

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

Average speed of the whole journey
= 900 ÷ 14
= 64 ⁴₁₄
= 64 ²₇ km/h

Answer(s): 64 ²₇ km/h