It was like:
A survey among 1000 Canadian sports fans was conducted and found out that each of them either a hockey fan or a lacrosse fan. 800 of them are hockey fans and 200 of them lacrosse fan. hence what's the probability of not being a hockey fan given that he/she is a lacrosse fan?
Someone complained of insufficient info. Though info is complete. As I finished typing and submitting the answer the question disappeared. Here's the solution for the student in need.
Among 1000 Canadian sports fans 800 are hockey fans, some of them are lacrosse fans , too some of them only hockey fans since there is none who is fan of neither hockey nor lacrosse
Therefore, (1000-800) = 200 are only lacrosse fans
Among 600 of lacrosse fans, 200 are only lacrosse fans, hence (600-200)= 400 are both fans of hockey and lacrosse
Therefore, only 800-400=400 are only hockey fans
Hence among 1000 sports fans...
read more

You are playing a game involving three dice. You can choose to bet on any number from 1 to 6.
I'll roll the three dice. If:
- none shows your number, you lose $1
- one shows your number, you win $1
- two show your number, you win $3
- three show your number, you win $5
What is the expected value of this game?
Email your answer so as not to ruin the challenge for others.

Today Nicole from Lenmore, CA, asked this question:
There are 5000 tires made including 200 that are defective if 4 tires are randomly selected, what is the probability that they are good?
Asked to use the method of redundancy but I'm having a hard time understanding how to write the equation and solve the problem.
The Wheeling Tire Company produced a batch of 5000 tires that includes exactly 200 that are defective.
a) If 4 tires are randomly selected for installation on a car, what is the probability that they are all good?
b) If 100 tires are randomly selected for shipment to an outlet, what is the probability that they are all good? Should the outlet plan to deal with defective tires returned by their customers?
And here's how I answered:
Hi Nicole, thanks for asking. Here's how I would do this problem.
1. Define your variables
T= total number of tires
D...
read more