A) 30 km/h
B) 35 km/h
C) 36 km/h
D) \[38\frac{4}{7}\text{km/h}\]
Correct Answer: D
Solution :
| \[\frac{1}{3}\]rd of journey \[=\frac{150}{3}=50\,\,\text{km}\] |
| Remaining \[\frac{2}{3}\]rd journey \[({{t}_{1}})=150-50=100\,\,\text{km}\] |
| Time taken in\[\frac{1}{3}\]rd Journey \[({{t}_{2}})=\frac{100}{45}=\frac{20}{9}\,\,\text{h}\] |
| Total time taken in whole journey |
| \[={{t}_{1}}+{{t}_{2}}=\frac{5}{3}+\frac{20}{9}=\frac{35}{9}\,\,\text{h}\] |
| Average speed \[=\frac{150}{\frac{35}{9}}=\frac{150\times 9}{35}=\frac{270}{7}=38\frac{4}{7}\,\,\text{km/h}\] |
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