2015 · Q80
A river 2.5 m deep and 45 m wide is flowing at the speed of 3.6 km/hour. The amount of water that runs into the sea per minute is
Elementary MathematicsMensuration
- A6650 {m}³
- B6750 {m}³
- C6850 {m}³
- D6950 {m}³
Explanation
This is a rate × cross-section flow problem. The river's cross-section is 2.5 × 45 m², and the water crosses it at 3.6 km/h = 3600/60 = 60 m/min. Volume per minute = 2.5 × 45 × 60 = 6750 m³. The trap is skipping the km/h to m/min conversion, which gives a wildly different figure. Hence option (b).