In a house two 60W electric bulbs are lighted for 4 hours, and three 100 W bulbs for 5 hours everyday. Calculate the electric energy consumed in 30 days.

Answer

To calculate the electric energy consumed in 30 days by the two types of bulbs, we will follow these steps:

### Step 1: Calculate the energy consumed by the 60W bulbs.
- **Number of bulbs**: 2
- **Power of each bulb**: 60W
- **Time each day**: 4 hours
- **Total days**: 30

The energy consumed by the 60W bulbs can be calculated using the formula:
\[ \text{Energy} = \text{Power} \times \text{Time} \]
For 2 bulbs:
\[ \text{Energy}_{60W} = 2 \times 60 \, \text{W} \times 4 \, \text{hours} \times 30 \, \text{days} \]
Convert hours to seconds for calculation:
\[ = 2 \times 60 \times 4 \times 30 = 14400 \, \text{Wh} \]

### Step 2: Calculate the energy consumed by the 100W bulbs.
- **Number of bulbs**: 3
- **Power of each bulb**: 100W
- **Time each day**: 5 hours
- **Total days**: 30

Using the same formula:
\[ \text{Energy}_{100W} = 3 \times 100 \, \text{W} \times 5 \, \text{hours} \times 30 \, \text{days} \]
\[ = 3 \times 100 \times 5 \times 30 = 45000 \, \text{Wh} \]

### Step 3: Calculate the total energy consumed.
Now, we add the energy consumed by both types of bulbs:
\[ \text{Total Energy} = \text{Energy}_{60W} + \text{Energy}_{100W} \]
\[ = 14400 \, \text{Wh} + 45000 \, \text{Wh} \]
\[ = 59400 \, \text{Wh} \]

### Step 4: Convert the total energy to kilowatt-hours (kWh).
Since 1 kWh = 1000 Wh, we convert:
\[ \text{Total Energy in kWh} = \frac{59400 \, \text{Wh}}{1000} = 59.4 \, \text{kWh} \]

### Final Answer:
The total electric energy consumed in 30 days is **59.4 kWh**.

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