15. In a planned study, there is a known population with a normal distribution,

 = 0, and  = 10. What is the predicted effect size (d ) if the researchers predict that those given an experimental treatment have a mean of

(a) -8,

(b) -5,

(c) -2,

(d) 0, and

(e) 10? For each part, also indicate whether the effect is approximately small, medium, or large.