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,
(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.



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
