NDA | Mathematics | Mean, Median and Mode

For which of the following sets of numbers do the mean, median and mode have the same value?

What is the mean deviation from the mean of the numbers 10, 9, 21, 16, 24?

If the standard deviation of the numbers -1, 0, 1, k is  where k > 0, then k is equal to:

The sum of deviations of n number of observations measured from 2.5 is 50 . The sum of deviations of the same set of observations measured from 3.5 is -50 . What is the value of n?

In a discrete data, if the median is double of the mean then, mode will how many times of the mean?