An educator determined the effect of instructions on the time required by subjects to solve the same puzzle. For two independent samples of ten subjects per group, mean solution times, in minutes, were longer for subjects given "difficult" instructions (M1=15.8, s=8.64) than for subjects given "easy" instructions (M2=9.0, s=5.01). A t stat of 2.15 led to the rejection of the null hypothesis.

(a). Given a pooled standard deviation of 7.06, calculate the value of standardized effect size.

(b). Provide the conclusion. What does it mean?