Mathematics 9709 · AS & A Level · Discrete random variables
Discrete random variables — practice question
Each year, Rajesh enters once for a ticket to a music festival. His chance of success in any given year is $0.3$, and the outcomes in different years are independent.
(a)[1]
Find the probability that Rajesh achieves his first success on his $7$th attempt.
(b)[2]
Find the probability that Rajesh’s first success occurs before his $6$th attempt.
(c)[2]
Find the probability that Rajesh is successful for the second time on his $10$th attempt.
Worked solution & mark scheme
This 5-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Accurate evaluation of $(0.7)^6 \times 0.3 = 0.0353$ (to at least 3 s.f.)” …