In a pond there are 20 lotus plants last year and through reproduction 8 new plants are added, taking the current population to 28. What is the birth rate?

Options

A. 4 offsprings per year
B. 0.4 offspring per lotus per year
C. 2.5 offspring per lotus per year
D. 25 offsprings per year

Answer

To solve the question regarding the birth rate of lotus plants in a pond, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Original Population**:
- The original population of lotus plants last year was 20.

2. **Identify the Current Population**:
- The current population of lotus plants after reproduction is 28.

3. **Calculate the Change in Population**:
- The change in population can be calculated by subtracting the original population from the current population:
\[ \text{Change in Population} = \text{Current Population} - \text{Original Population} = 28 - 20 = 8 \]

4. **Use the Birth Rate Formula**:
- The formula for birth rate is given by:
\[ \text{Birth Rate} = \frac{\text{Change in Population}}{\text{Original Population}} \]
- Substituting the values we have:
\[ \text{Birth Rate} = \frac{8}{20} \]

5. **Simplify the Fraction**:
- Simplifying \(\frac{8}{20}\):
\[ \text{Birth Rate} = 0.4 \]

6. **Conclusion**:
- The birth rate of the lotus plants is 0.4 per lotus per year.

### Final Answer:
The birth rate is **0.4**.

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