Onr group of students used simulation programs, while another group received a tutorial. Scores on the exam were compared.

Statistic Simulation Tutorial

Mean Score x1=8.6 x2=10.6

Sample std. dev. s1=2.0 s2=1.9

Number of students n1=30 n2=30

Construct a 99 percent confidence interval for the true difference in mean scores. (round your answers to 2 decimal places. Negative values should be indicated by a minus sign.)

The 99% confidence interval is from _______ to ______