Cancer is a global medical concern and around half of the patients diagnosed with cancer do succumb to it.

There are many types of cancer treatments including chemotherapy, hormone therapies, biological therapies, and bisphosphonates. A cancer treatment center selected 20 patients to receive an experimental therapy, which is believed to be better than the current treatments. The experimental therapy has 3-year historically survival rate of 10%.

a. What is the probability that all selected cancer patients died from cancer after the treatment?

b. If the survival rate decreased to 4%, determine the probability that all selected cancer patients died from cancer after the treatment.