18. Ivana has two identical dice and on the faces of each are the numbers $-3,-2,-1,0,1,2$. If she throws her dice and multiplies the results, what is the probability that their product is negative?
A $\frac{1}{4}$
B $\frac{11}{36}$
C $\frac{1}{3}$
D $\frac{13}{36}$
E $\frac{1}{2}$
18. C We can get a negative product if the first die is negative and the second positive, with probability $\frac{3}{6} \times \frac{2}{6}=\frac{6}{36}$, or if the first die is positive and the second is negative, with probability $\frac{2}{6} \times \frac{3}{6}=\frac{6}{36}$. Together this gives a probability of $\frac{12}{36}=\frac{1}{3}$.