Two groups of 100 students are randomly divided into two groups of 50. The experimental group receives a new teaching method, the control group...

Two groups of 100 students are randomly divided into two groups of 50. The experimental group receives a new teaching method, the control group receives no intervention.

One month later, test results reveal the students test levels are 0.64 and 0.40 respectively.

Is the teaching method effective? use a=0.5.

State the difference between the two groups using a 95 % confidence level.