Using a calculator, you should get a sample standard deviation of approximately 2.5 hours
If you want to find the standard deviation by hand, you need to do the following steps
The teacher data set has a sample standard deviation of roughly 2.5 hours; compare this with the sample standard deviation of the students 1.9 hours, and we see that the teacher data set is more spread out. The larger the standard deviation is, the more spread out the data set will be.