Answer :
Let's call event A buyers under 13 years old, and event B is a clock scented like cinnamon.
First, we find the probability of A and B
[tex]P(A\cap B)=P(A)\cdot P(B)=\frac{7}{13}\cdot\frac{6}{13}=\frac{42}{169}[/tex]Then, we use the conditional probability formula to find the probability of A given B.
[tex]P(A|B)=\frac{P(A\cap B)}{P(B)}=\frac{\frac{42}{169}}{\frac{6}{13}}=\frac{42\cdot13}{169\cdot6}=\frac{7}{13}[/tex]