The speed of a bus is 54 km/h if stoppages are excluded and the speed of bus is 45 km/h if stoppages are included. For how many minutes does the bus stop per hour ?

Options

A. 8
B. 10
C. 12
D. 15

Answer

To solve the problem of how many minutes the bus stops per hour, we can follow these steps:

### Step 1: Identify the speeds
- The speed of the bus without stoppages is 54 km/h.
- The speed of the bus with stoppages included is 45 km/h.

### Step 2: Calculate the difference in speed
- The difference in speed when stoppages are included and excluded is:
\[ \text{Difference} = \text{Speed without stoppage} - \text{Speed with stoppage} = 54 \text{ km/h} - 45 \text{ km/h} = 9 \text{ km/h} \]

### Step 3: Use the formula for stoppages
- The formula to find the time the bus stops per hour is:
\[ \text{Time stopped per hour} = \frac{\text{Difference in speed}}{\text{Speed without stoppage}} \]
- Substituting the values we have:
\[ \text{Time stopped per hour} = \frac{9 \text{ km/h}}{54 \text{ km/h}} = \frac{1}{6} \text{ hours} \]

### Step 4: Convert hours to minutes
- To convert the time from hours to minutes, we multiply by 60:
\[ \text{Time stopped in minutes} = \frac{1}{6} \text{ hours} \times 60 \text{ minutes/hour} = 10 \text{ minutes} \]

### Conclusion
- Therefore, the bus stops for **10 minutes per hour**.

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