In a completed study, there is a known population with a normal distribution, = 30, and o = 12. What is the estimated effect size if a sample given an experimental procedure has a mean of (a) 18, (b) 24, (c) 30, (d) 35, and (e) 40? For each part, also indicate whether the effect is approximately small, medium, or large. (a) d =(Type an integer or decimal rounded to three decimal places as needed.)