🛠️ Scheduled Maintenance | We’ll be undergoing scheduled maintenance and upgrades between 00:00 PST Jan 26th until 00:00 PST Jan 28th. There may be brief interruption of services in that period. We apologize for the inconvenience.

The 365 Data Science team is proud to invite you to our own community forum. A very well built system to support your queries, questions and give the chance to show your knowledge and help others in their path of becoming Data Science specialists.
Anybody can ask a question
Anybody can answer
The best answers are voted up and moderated by our team

In Bullseye question from Probability

In Bullseye question from Probability


Hi there i am bit poor at probability so i have doubt on bullseye numerical outcomes question.
how does probability of A is 0.5, similarly B is 0.4 and C is 0.1.
pls clarify this doubt of mine.

1 Answer

365 Team

Hey Aravind, 
Thanks for reaching out!
So, the focus of that particular lecture is about expected values, so we’re just being “given” the probabilities of each outcome. The idea was to assume that the probabilities of events A, B and C are so and so, and focus on the expected value formula. 
However, the rationale we used for the ballpark figure probabilities came from what part of the area of the dart board they cover (assuming each region is equally wide). Hence, if the inner radius is 1, the intermediate one is 2 and the outer most is 3, then the areas of the 3 zones would be:
1.) 1^2*pi = pi
2.) 2^2*pi – (area of the inner circle) = 4*pi – pi = 3*pi
3.) 3^2*pi – (area of the first two layers) = 9*pi – 4*pi = 5*pi
Thus, the ratio of the 3 zones, would be 1:3:5. To make the numbers “nicer”, we tweaked it to 1:4:5 and got 0.1, 0.4 and 0.5 respectively.
Hope this helps understand our rationale. 
365 Vik