Historically, victims of the Ebola virus had a 30% chance of survival.

a. A new treatment is tested on three victims, and at least two of them survive. What is the probability of this happening, if the treatment is not effective? (2 points)

b. The new treatment is tested on six victims, and at least four of them survive. Does this provide more convincing evidence that the treatment is effective? Why or why not? (2 points)