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A train travels at a speed of 30 km/hr for 12 minutes and at a speed of 45 km/hr for the next 8 minutes. The average speed of the train for this journey is :
Answer & Solution
Correct Answer:
Option
B
Total distance travelled :
$$\eqalign{ & = \left( {30 \times \frac{{12}}{{60}} + 45 \times \frac{8}{{60{\text{ }}}}} \right){\text{ km}} \cr & = {\text{12 km}} \cr} $$
Total time taken :
= (12 + 8) min
= 20 min
= $$\frac{1}{3}$$ hr
∴ Average speed :
= (12 × 3) km/hr
= 36 km/hr
$$\eqalign{ & = \left( {30 \times \frac{{12}}{{60}} + 45 \times \frac{8}{{60{\text{ }}}}} \right){\text{ km}} \cr & = {\text{12 km}} \cr} $$
Total time taken :
= (12 + 8) min
= 20 min
= $$\frac{1}{3}$$ hr
∴ Average speed :
= (12 × 3) km/hr
= 36 km/hr
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