A teacher wanted to know how well the gifted students in her class perform relative to her other classes. She administers a standardized test with a mean of 50 points and standard deviation of 10...

A teacher wanted to know how well the gifted students in her class perform relative to her other classes. She administers a standardized test with a mean of 50 points and standard deviation of 10 points. Her class of 31 students has an average score of 55. Test if this new sample mean has statistical significance at the 95 % confidence level.