Elijah took 6 hours to travel from Country Y to Country Z at 55 km/h. Then he travelled from Country Z to another country at 1.6 times his original speed. 40% of the distance from Country Y to Country Z is equal to ¹₆ 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
= 6 x 55
= 330 km

Speed from Country Z to another country
= 1.6 x 55
= 88 km/h

40% = ⁴⁰₁₀₀ = ²₆

²₅ Distance from Country Y to Country Z = ¹₆ Distance from Country Z to next country
²₅ Distance from Country Y to Country Z = ²₁₂ Distance from Country Z to next country

5 u = 330
1 u = 330 ÷ 5 = 66

Distance from Country Z to the next country
= 12 u
= 12 x 66
= 792 km

Time taken from Country Z to the next country
= 792 ÷ 88
= 9 h

Total distance of the whole journey
= 330 + 792
= 1122 km

Total time taken for the whole journey = 6 + 9 = 15 h

Average speed of the whole journey
= 1122 ÷ 15
= 74 ¹²₁₅
= 74 ⁴₅ km/h

Answer(s): 74 ⁴₅ km/h