Question 1192042
a. 10 red/20 overall probability is 0.5
b. blue or black are also 10 balls, so the answer is also 0.5
c. prob. first is black is 4/20 and second one also black is 3/19. The answer is their product, 12/380, which may be reduced or put into decimal form.
It is also 4C2*/20C2=6/190, the reduced form of the above