A train covers a fixed distance in 45 minutes at an average speed of 160 km/h. Due to a bridge repair, the route is changed, increasing the distance by 25%. If the train must still reach its destination in 45 minutes, what should its new average speed be in km/h?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 200 km/h.
Original distance = Speed × Time
Time = 45 minutes = 45/60 = 3/4 hours
Original distance = 160 × 3/4 = 120 km
New distance = 120 + 25% of 120
= 120 + 25/100 × 120 = 150 km
New average speed = Distance ÷ Time
= 150 ÷ (3/4)
= 200 km/h