So I have this raw data for a case study:

Note: 1 stands for average weight and 2 for overweight.
I need to calculate the following:
- What is the mean expected time spent for the average-weight patients? What is the mean expected time spent for the overweight patients?
- What is the difference in means between the groups? By approximately how many standard deviations do the means differ?
I have already solved the first one and the first part of the 2nd question. However how do I answer the 2nd part of the 2nd question?(the standard deviations part)
Answers:
1) Average weight mean = 31.36; overweight mean = 24.74
2) Difference = 6.62; they differ by 0.68 standard deviations