Michael took 5 hours to travel from Country M to Country N at 60 km/h. Then he travelled from Country N to another country at 1.5 times his original speed. 65% 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
= 5 x 60
= 300 km

Speed from Country N to another country
= 1.5 x 60
= 90 km/h

65% = ⁶⁵₁₀₀ = ¹³₅

¹³₂₀ Distance from Country M to Country N = ¹₆ Distance from Country N to next country
¹³₂₀ Distance from Country M to Country N = ¹³₇₈ Distance from Country N to next country

20 u = 300
1 u = 300 ÷ 20 = 15

Distance from Country N to the next country
= 78 u
= 78 x 15
= 1170 km

Time taken from Country N to the next country
= 1170 ÷ 90
= 13 h

Total distance of the whole journey
= 300 + 1170
= 1470 km

Total time taken for the whole journey = 5 + 13 = 18 h

Average speed of the whole journey
= 1470 ÷ 18
= 81 ¹²₁₈
= 81 ²₃ km/h

Answer(s): 81 ²₃ km/h