Then the number of people in this survey is 54;

(2) The frequency of ∫ C class is 7 27,

∴ Class C frequency is 54× 7 27 =14;

(3) The number of people in Class B is 54× 527 =10; Grade c has 14 people; There are 54× 6 27 = 12 people in grade d;

There are 54× 5 27 = 10 people in grade e,

Complete the bar chart, as shown:

(4) According to the meaning of the question: 432× 4+5+7 27 =256 (person),

Then there are 256 people in Grade A, Grade B and Grade C.

So the answer is: (1) 54; (2) 14; 7 27