The table gives the frequency distribution of marks obtained by a group of students in a test. Marks 3 4 5 6 7 8 Frequency 5 x - 1 x 9 4 1 If the mean is 5,...

The table gives the frequency distribution of marks obtained by a group of students in a test.

If the mean is 5,

(a) Calculate the value of x;

(b) Find the : (i) mode ; (ii) median of the distribution.

(c) If one of the students is selected at random, find the probability that he scored at least 7 marks.