When a train moves at an average speed of 100 kmph it reaches its destination on time. When its average speed becomes 80 kmph, then it reaches its destination 20 minutes late. Find the length of journey rounded to two decimal places. Choose the correct option: A) 99.33 km B) 133.33 km C) 125.33 km D) 156.66 km E) None
Sol.   Difference between timings = 20 min = 1/3 hr.   Let the length of journey be x km.   Then, x/80 - x/100 = 1/3   â‡” 5x - 4x = 133.33   â‡” x = 133.33 km.   Answer 133.33 km
<result>B</result>
When a train moves at an average speed of 100 kmph it reaches its destination on time. When its average speed becomes 80 kmph, then it reaches its destination 20 minutes late. Find the length of journey rounded to two decimal places.