A train running at a speed of 100 miles/hour, takes 10 hours to reach its destination. After covering quarter of the distance, it starts raining and the train has to be slowed to speed of 75 miles/hour. What is the total journey duration?
Choices: A) 10 B) 11.5 C) 12.5 D) 13.5 E) 15
Distance to destination = 100 X 10 = 1000 miles.   Distance remaining when it starts to rain = 1000 - 250= 
<gadget id="calculator">1000 - 250</gadget>
<output>750</output>
750 miles.   Speed for remaining distance= 75 miles / hour.   Time taken to cover remaining distance = 750 / 75= 
<gadget id="calculator">750 / 75</gadget>
<output>10</output>
10 hours.   Total duration of the journey= 2.5 + 10= 
<gadget id="calculator">2.5 + 10</gadget>
<output>12.5</output>
12.5 hours.   The correct option is 12.5.
<result>C</result>
A train running at a speed of 100 miles/hour, takes 10 hours to reach its destination. After covering quarter of the distance, it starts raining and the train has to be slowed to speed of 75 miles/hour. What is the total journey duration?