The mean (or average) of observations is the sum of the values of all the observations divided by the total number of observations.
The mean for grouped data is given by:
[tex]Mean=∑(f_i.x_i)/∑f_i[/tex]
• So; first we calculate each class mark xi, as:
(0 + 3)/2 = 1.5
(4 + 7)/2 = 5.5
(8 + 11)/2 = 9.5
• Now; we calculate fixi, as:
1.5 x 12 = 18
5.5 x 20 = 110
9.5 x 8 = 76
• Hence, the mean is given by:
[tex]Mean=\frac{18+110+76}{12+20+8}=5.10[/tex]
ANSWER
5.10
