Statistics question

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A private tutoring company has made the claim that its tutoring package will improve GRE Verbal test scores by at least 25 points. A graduate student in psychology hears this claim and decides to test their theory. After gathering 10 undergraduate students who are willing to participate in the program, he wants to predict the effect size for an increase of 25 points, assuming a GRE Verbal test mean in the population of 462 and a standard deviation of 119. What is the predicted effect size for a projected increase of 25 points?