6) A group of 12 students were instructed in calculus using traditional methods. At the end of the course these students were given a standardized test to determine their understanding of calculus. The average score of these 12 students on the test was 69.5 with a standard deviation of 8.54. A separate group of 10 students were taught calculus using a new experimental teaching method. The average score on the standardized test given at the end of the course was 79.6 with a standard deviation of 9.29. Using this information, find a 95% confidence interval for the difference in population mean scores on the standardized test of the two teaching methods.

Choose what you believe is the best answer from the following answers

i) (-12.86, -7.59 )

ii) (-17.71, -2.69)

iii) (-18.04, -2.16)

iv) (-12.71, -7.69)

v) none of these.