Question

the incomes of a group of 10,000 persons were found to be normally distributed with mean equal to rs. 750 and standard deviation equal to rs. 50. what was lowest income among the richest 250?

Answer 1

To find the lowest income among the richest 250, calculate the z-score for each income value and find the 250th smallest z-score. Then, use the z-score formula to convert the z-score back into an income value.

Step-by-step explanation:

To find the lowest income among the richest 250, we need to calculate the z-score for the income of each person in the group. The z-score measures how many standard deviations an individual's income is from the mean. We can then sort the z-scores in ascending order and find the z-score corresponding to the 250th person. Finally, we can use the z-score formula to convert the z-score back into an income value.

To calculate the z-score for each income, we can use the formula:
z = (x - mean) / standard deviation

Once we have the z-scores, we can arrange them in ascending order, and the z-score corresponding to the 250th person will be the 250th smallest z-score. We can then use the z-score formula to find the income:

lowest income = (z-score * standard deviation) + mean