A running man crosses a bridge of length 500 meters in 4 minutes. At what speed he is running?

Options

A. 8.5 km/hr
B. 7.5 km/hr
C. 9.5 km/hr
D. 6.5 km/hr

Answer

To find the speed of the running man who crosses a bridge of length 500 meters in 4 minutes, we can follow these steps:

### Step 1: Identify the given values
- Distance (D) = 500 meters
- Time (T) = 4 minutes

### Step 2: Convert the distance from meters to kilometers
To convert meters to kilometers, we use the conversion factor \(1 \text{ km} = 1000 \text{ meters}\).
\[ \text{Distance in km} = \frac{500 \text{ meters}}{1000} = 0.5 \text{ km} \]

### Step 3: Convert the time from minutes to hours
To convert minutes to hours, we use the conversion factor \(1 \text{ hour} = 60 \text{ minutes}\).
\[ \text{Time in hours} = \frac{4 \text{ minutes}}{60} = \frac{1}{15} \text{ hours} \]

### Step 4: Use the formula for speed
The formula for speed (S) is given by:
\[ S = \frac{\text{Distance}}{\text{Time}} \]
Substituting the values we found:
\[ S = \frac{0.5 \text{ km}}{\frac{1}{15} \text{ hours}} = 0.5 \text{ km} \times 15 = 7.5 \text{ km/h} \]

### Step 5: Conclusion
The speed of the running man is \(7.5 \text{ km/h}\).