Increasing the frequency of observations in the tails of a distribution will increase the standard deviation. why?

Because tha data placed in the tail of the distribution is the most separated data from the central stats, so, variation measures will be affected if we increase the representation of the least central values.

Remember that the standard deviation represents the degree of deviation regarding the mean is the data. So, if we increase data in the tails, we will increase the most ranged data, so the variation will be higher, which means the standard deviation will also increase.

since proposition states that a number is greater than 25, if is true then the number must actually be greater than 25.

this implies that all possible options, except 24, can be accepted