The average consumption of petrol for a car for 7 months is 110 litres and for next 5 months it is 86 litres .The average monthly consumption is :

Options

A. 96 L
B. 98 L
C. 100 L
D. 102 L

Answer

To find the average monthly consumption of petrol for the car over the entire period of 12 months, we can follow these steps:

### Step 1: Calculate the total consumption for the first 7 months.
The average consumption for the first 7 months is given as 110 litres.

To find the total consumption for these 7 months, we use the formula:
\[ \text{Total Consumption} = \text{Average Consumption} \times \text{Number of Months} \]
\[ \text{Total Consumption for 7 months} = 110 \, \text{litres} \times 7 = 770 \, \text{litres} \]

### Step 2: Calculate the total consumption for the next 5 months.
The average consumption for the next 5 months is given as 86 litres.

Using the same formula:
\[ \text{Total Consumption for 5 months} = 86 \, \text{litres} \times 5 = 430 \, \text{litres} \]

### Step 3: Calculate the overall total consumption for 12 months.
Now, we can find the total consumption for all 12 months by adding the total consumption of the first 7 months and the total consumption of the next 5 months:
\[ \text{Total Consumption for 12 months} = 770 \, \text{litres} + 430 \, \text{litres} = 1200 \, \text{litres} \]

### Step 4: Calculate the average monthly consumption for the entire 12 months.
To find the average monthly consumption over the 12 months, we use the formula:
\[ \text{Average Monthly Consumption} = \frac{\text{Total Consumption}}{\text{Total Number of Months}} \]
\[ \text{Average Monthly Consumption} = \frac{1200 \, \text{litres}}{12} = 100 \, \text{litres} \]

### Final Answer:
The average monthly consumption of petrol for the car over the entire period of 12 months is **100 litres**.

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