Given that there is more area under the t distribution pdf curves in these extreme regions, this implies that there is a higher probability that the value of a random variable with a t distrib...Given that there is more area under the t distribution pdf curves in these extreme regions, this implies that there is a higher probability that the value of a random variable with a t distribution would be this far away from the center compared to a standard normal random variable, meaning that there is greater spread in the values from the mean and hence a larger variance for the t distribution.