The population of a town is decreasing at a rate of 10% per annum. If the population two years ago was 20,000, what is the present population?

Options

A. 16200
B. 16000
C. 15200
D. 15000

Answer

To find the present population of the town, we will calculate the population year by year, taking into account the 10% annual decrease.

### Step 1: Calculate the population one year ago
The population two years ago was 20,000. Since the population decreases by 10% per annum, we need to find out what the population was one year ago.

1. **Calculate 10% of 20,000**:
\[ 10\% \text{ of } 20,000 = \frac{10}{100} \times 20,000 = 2,000 \]

2. **Subtract this from the population two years ago**:
\[ \text{Population one year ago} = 20,000 - 2,000 = 18,000 \]

### Step 2: Calculate the present population
Now we will calculate the present population based on the population one year ago, which is 18,000.

1. **Calculate 10% of 18,000**:
\[ 10\% \text{ of } 18,000 = \frac{10}{100} \times 18,000 = 1,800 \]

2. **Subtract this from the population one year ago**:
\[ \text{Present Population} = 18,000 - 1,800 = 16,200 \]

### Final Answer
The present population of the town is **16,200**.

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