The ratio between the speeds of two trains is 7:8. If the second train runs…
2024
The ratio between the speeds of two trains is 7:8. If the second train runs 400 kms in 4 hours, then the speed of the first train is :
- A.
70 km/hr
- B.
75 km/hr
- C.
84 km/hr
- D.
87.5 km/hr
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Correct answer: D
Key idea: use the distance/time to find the second train's speed, then apply the 7:8 ratio.
Compute the second train's speed: 400 km ÷ 4 hr = 100 km/hr.
Let the speeds be 7x and 8x. Since the second speed is 8x = 100, solve for x: x = 100 ÷ 8 = 12.5.
Find the first train's speed: 7x = 7 × 12.5 = 87.5 km/hr.
Answer: 87.5 km/hr