The probability that both show a blue marble is $\dfrac{1}{2}\times \dfrac{1}{4}=\dfrac{1}{8}$. The probability that both show a red marble is $\dfrac{1}{2}\times \dfrac{2}{4}=\dfrac{1}{4}$. Therefore, the probability is $\dfrac{1}{4}+\dfrac{1}{8}=\dfrac{3}{8}$. 
Adele has $1$ blue and $1$ red marble in her hand. Bobby has $1$ blue, $1$ yellow, and $2$ red marbles in his hand. Each of them randomly picks a marble to show the other. What is the probability that the colors are the same? 
  - $\dfrac{1}{4}$ 
  - $\dfrac{1}{3}$ 
  - $\dfrac{3}{8}$ 
  - $\dfrac{1}{2}$ 
  - $\dfrac{2}{3}$ 