Here is the instruction:

Use the data from the table to calculate the number of hours of daylight for one day per week throughout the year (52 data points). Be sure to use the same day of the week so that your data points are evenly spaced 7 days apart.

Does this mean...
Jan. 1
Jan. 7
Jan. 14
Jan.21
Jan.28
Etc..

Or

Jan.1
Jan. 8
Jan.15
Jan.22
Jan.29
Etc..