Statistical power/Data analysis tutorial

Power

 * Power.xls
 * If I am using a confidence interval of 95% and I want a power level .8, what would be the minimum sample size to detect a standardised mean difference of .3?
 * If I am using a confidence interval of 99% and I want a power level of .7, what would be the minimum sample size to detect an effect size of .7?
 * If I am using a confidence interval of 90% and I want a power level of .9, with a sample size of 200, what effect size will I be able to detect?
 * If I am using a confidence interval of 95% and I will have a sample size of 50, and I want a power level of .8, what effect size will I be able to detect?