We have just conducted a study comparing cognitive development of low- and normal-birthweight babies who have reached one year of age. Using a scale we devised, we found that the sample means of the...

We have just conducted a study comparing cognitive development of low- and normal-birthweight babies who have reached one year of age. Using a scale we devised, we found that the sample means of the two groups were 25 and 30 respectively, with a pooled standard deviation of 8. Assume that we wish to replicate this experiment with 20 participants in each group. If we assume that the true means and standard deviations have been estimated exactly, what is the a priori probability that we will find a significant difference in our replication?