Let us first assume A, B and C be the set of people who like product A, product B and product C respectively

Now, it is given in the question that:

Number of students who like product A, n (A) = 21

Number of students who like product B, n (B) = 26

Number of students who like product A, n (C) = 29

Number of students who like both product A and B,

Number of students who like both product A and B,

Number of students who like both product A and B,

Number of students who like all three product,

On the basis of given condition the venn diagram for the following question can be drawn as follows:

From the venn diagram, it can clearly be seen that:

Number of students who only like product C = {29 – (4 + 8 + 6)}

= {29 – 18}

= 11 students