The following table shows the marks obtained (out of 10) by 40 students in a weekly mathematics test.
Marks (x) : 0 1 2 3 4 5 6 7 8 9 10
Frequency (f) : 1 2 3 5 6 7 6 4 3 2 1
Answer the following questions based on the data given above.
(i) Find the total number of marks scored by all the students together.
(ii) Calculate the mean mark obtained by the students, correct to two decimal places.