One sample t test results

P value and statistical significance:

The two-tailed P value equals 0.00000118

By conventional criteria, this difference is considered to be very statistically significant.

Confidence interval:

The hypothetical mean is 75.000000000

The actual mean is 68.416666700

The difference between these two values is −6.583333300

The 95% confidence interval of this difference:

From −8.102876501 to −5.063790099

Intermediate values used in calculations:

t = −9.5356

df = 11

standard error of difference = 0.690