A school psychologist uses a well-being scale to see if the level of well-being in fourth graders who have been taught positive psychology strategies is higher than that of fourth graders in general at the school. The results of previous testing indicate that fourth graders at the school usually have a score of 5 on the scale, but the variance is unknown. The current sample of 25 fourth graders has a mean well-being score of 6.2 If the unbiased estimate of the population's variance is 10, the variance of the distribution of means is 100/24 = 4.17 100/25 = 4 10/24 = 0.42 10/25 = 0.40