Find the mean of the students for the following distribution

Find the mean marks of students for the following distribution. {:(" Marks "," Number of students "),(" 0 and above "," "80),(" 10 and above "," "77),(" 20 and above "," "72),(" 30 and above "," "65),(" 40 and above "," "55),(" 50 and above "," "43),(" 60 and above "," "28),(" 70 and above "," "16),(" 80 and above "," "10),(" 90 and above "," "8),(" 100 and above "," "0):}

Find the mean for the following distribution :

Find the mean for the following distribution :

Find the mean for the following distribution :

Find the mean for the following distribution:

Find the mean for the following distribution.

Find the mean of the following distribution

Find the mean of the following distribution

Find the missing frequencies for the following distribution if the mean of the distribution is 34.

Find the value of if the mean of the following distribution is 7.5