Final answer:
The richest 25% of country 'x' earn 70% of the total income, which is not one of the provided options. The given options seem to have a mistake as none of them match the correct calculation.
Step-by-step explanation:
To determine the percentage of the total income earned by the richest 25% in country 'x', we can analyze the given income distribution data. The data tells us the following: the poorest 25% earn 3% of the total income, the poorest 50% earn 12% of the total income, and the poorest 75% earn 30% of the total income. To find the share for the richest 25%, we need to understand that the sum of the income shares for all quarters of the population should be 100% since they represent the entire population. Given that the poorest 75% earn 30% of the income, we can subtract this from 100% to find the income share of the richest 25%.
100% - 30% = 70%
Therefore, the richest 25% earn 70% of the total income. This is not one of the options provided, indicating there may have been a mistake in the options given or in the question itself. The correct answer based on the given data is 70% and not any of the options provided (85%, 82%, 15%, 18%).