Some form of prophylaxis is said to be 90% effective at prevention during one year's treatment. If the degrees of effectiveness in different years are independent, show that the treatment is more likely than not to fail within 7 years

Question 10: [2 Marks]: Some form of prophylaxis is said to be 90% effective at prevention during one year's treatment. If the degrees of effectiveness in different years are independent, show that the treatment is more likely than not to fail within 7 years