Eric took 3 hours to travel from Country Y to Country Z at 70 km/h. Then he travelled from Country Z to another country at 1.2 times his original speed. 50% of the distance from Country Y to Country Z is equal to ¹₄ of the distance from Country Z to the next country. Find the average speed for the whole journey and express it as a mixed number.
Distance he travelled from Country Y to Country Z
= 3 x 70
= 210 km

Speed from Country Z to another country
= 1.2 x 70
= 84 km/h

50% = ⁵⁰₁₀₀ = ¹₃

¹₂ Distance from Country Y to Country Z = ¹₄ Distance from Country Z to next country
¹₂ Distance from Country Y to Country Z = ¹₄ Distance from Country Z to next country

2 u = 210
1 u = 210 ÷ 2 = 105

Distance from Country Z to the next country
= 4 u
= 4 x 105
= 420 km

Time taken from Country Z to the next country
= 420 ÷ 84
= 5 h

Total distance of the whole journey
= 210 + 420
= 630 km

Total time taken for the whole journey = 3 + 5 = 8 h

Average speed of the whole journey
= 630 ÷ 8
= 78 ⁶₈
= 78 ³₄ km/h

Answer(s): 78 ³₄ km/h