Boojho walks to his school which is at a distance of 3 km from his home in 30 minutes. On reaching he finds that the school is closed and comes back by a bicycle with his friend and reaches home in 20 minutes. His average speed in km/h is

Options

A. 8.3
B. 7.2
C. 5
D. 3.6

Explanation

To find Boojho's average speed, we need to calculate the total distance he traveled and the total time he took for the entire journey.

### Step 1: Calculate the total distance traveled
Boojho walks to school and then returns home. The distance to the school is 3 km. Therefore, the total distance traveled is:
- Distance to school = 3 km
- Distance back home = 3 km
- Total distance = 3 km + 3 km = 6 km

### Step 2: Calculate the total time taken
Boojho takes 30 minutes to walk to school and 20 minutes to return home. Therefore, the total time taken is:
- Time to school = 30 minutes
- Time back home = 20 minutes
- Total time = 30 minutes + 20 minutes = 50 minutes

### Step 3: Convert total time from minutes to hours
To calculate average speed in km/h, we need to convert the total time from minutes to hours:
- Total time in hours = 50 minutes ÷ 60 minutes/hour = 50/60 hours = 5/6 hours

### Step 4: Calculate the average speed
Average speed is calculated using the formula:
\[ \text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time}} \]
Substituting the values we have:
\[ \text{Average Speed} = \frac{6 \text{ km}}{5/6 \text{ hours}} \]
To divide by a fraction, we multiply by its reciprocal:
\[ \text{Average Speed} = 6 \text{ km} \times \frac{6}{5} = \frac{36}{5} \text{ km/h} = 7.2 \text{ km/h} \]

### Final Answer
Boojho's average speed is **7.2 km/h**.

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