Answer:
A loss of 1.8$
Explanation:
In the bag in this problem, we have:
r = 1 (number of red marbles)
w = 7 (number of white marbles)
b = 2 (number of blue marbles)
n = r + w + b = 1 + 7 + 2 = 10 (number of total marbles)
So, the probabilities of choosing a red, a white or a blue marble are:
(probability of choosing a red marble)
(probability of choosing a white marble)
(probability of choosing a blue marble)
The winning associated to each probability are:
+$5 if the marble is red
-$3 if the marble is white
-$1 if the marble is blue
So the expected winning can be calculated as follows:

So, he can expect a loss of 1.8$.