Explanation: To understand the concept of the death rate in Bihar and the percentage increase from one year to the next, we need to delve into the historical demographic data of the state. The death rate is a critical measure in demography, reflecting the number of deaths per 1,000 individuals in a given population over a specific period, typically a year.
In this context, the question provides a specific scenario where the death rate in Bihar in 1967 is compared to the death rate in 1968. The percentage increase is calculated using the formula:
\[ \text{Percentage Increase} = \left( \frac{\text{Death Rate in 1967} - \text{Death Rate in 1968}}{\text{Death Rate in 1968}} \right) \times 100 \]
To solve this problem, we need the actual death rates for both years. Let's assume the death rate in 1967 was \( D_{1967} \) and in 1968 was \( D_{1968} \). The percentage increase is then calculated as:
\[ \text{Percentage Increase} = \left( \frac{D_{1967} - D_{1968}}{D_{1968}} \right) \times 100 \]
Given that the correct answer is 34%, we can infer that the death rate in 1967 was 34% higher than in 1968. This means that if the death rate in 1968 was \( D_{1968} \), then the death rate in 1967 was \( D_{1967} = D_{1968} + 0.34 \times D_{1968} \).
For example, if the death rate in 1968 was 10 deaths per 1,000 people, then the death rate in 1967 would be:
\[ D_{1967} = 10 + 0.34 \times 10 = 13.4 \]
Thus, the death rate in 1967 was 13.4 deaths per 1,000 people, which is 34% higher than the 10 deaths per 1,000 people in 1968.
Understanding the concept of percentage increase is crucial for solving such problems. It involves comparing two values and determining the relative change between them. In this case, the death rate in 1967 was significantly higher than in 1968, reflecting a 34% increase. This type of analysis is important in demography and public health studies to understand trends and patterns in mortality rates over time.
The other options (30%, 36%, and 40%) are incorrect because they do not accurately reflect the percentage increase based on the given data. It is essential to carefully calculate and verify the percentage increase to avoid common misconceptions and errors in interpretation.