Question

I don’t know how to solve this problem

Answer 1

The draws are independent, so

$P(\text{red then blue})=P(\text{red})\cdot P(\text{blue})$

There is a total of 11 marbles in the bag, so

$P(\text{red})=\dfrac3{11}$

and

$P(\text{blue})=\dfrac5{11}$

So

$P(\text{red then blue})=\dfrac{15}{121}$