In a survey it was found that 21 people liked product A, 26 liked product B and 29 liked product C.

Let A, B, and C be the set of people who like product A, product B, and product C respectively.

Accordingly, $n(\mathrm{~A})=21, n(\mathrm{~B})=26, n(\mathrm{C})=29, n(\mathrm{~A} \cap \mathrm{B})=14, n(\mathrm{C} \cap \mathrm{A})=12$

$n(B \cap C)=14, n(A \cap B \cap C)=8$

The Venn diagram for the given problem can be drawn as

It can be seen that number of people who like product C only is

$\{29-(4+8+6)\}=11$