How can I add certain elements in this 2d data structure and calculate a mean

[TheOddCircle]

# ------------------------------------------------------------
# Import libraries
# ------------------------------------------------------------
# =====> Write your code here
mean = 0
index = 0
# ------------------------------------------------------------
# Constants
# ------------------------------------------------------------
# =====> Write your code here
Pass = (mean >= 50)
Fail = (mean <= 49)
# ------------------------------------------------------------
# Global variables
# ------------------------------------------------------------
myClass = [["Lang", "Carla", 49, 71, 95, 50],
           ["Bucklund", "Pia", 86, 78, 83, 64],
           ["Lang", "Jason", 95, 57, 92, 62],
           ["Dimitrousis", "Hector", 93, 45, 89, 96],
           ["Owens", "Sunna", 45, 50, 46, 54],
           ["Goldin", "Sandra", 25, 60, 45, 55],
           ["Giles", "Seth", 67, 73, 93, 64],
           ["Gurillo", "Melanie", 88, 88, 62, 79],
           ["Rykiel", "Kari", 67, 92, 54, 86],
           ["Shailes", "Dennis", 56, 70, 84, 62]]

# =====> Write your code here
for mean in myClass:
    for total in myClass[index:]
    total = myClass[2] + myClass[3] + myClass[4] + myClass[5]
    index += 1
    print (total)

This was my attempt at doing it by indexing the first row and moving down by adding one each time to the 2d data structure place. I want to be able to calculate the mean of the last four numbers in the data structure. The numbers would be [2][3][4][5] but I do not know how to calculate it each time for each row on the list. I tried using for mean in myClass[index]: but it would give no extra help. Any ideas