probability estimate

1. Representative sample - how to decide

I am interested in understanding some of the Covid 19 statistics being thrown around. What I want to know is how to figure out whether a sample that was used to generate probabilities was actually representative of the population that was supposed to be sampled. I want to do this 'backwards' so...
2. Statistical significance/ probability

I have data for number of different vehicle types (cars, 2-Wheelers, 3-Ws, other) and which vehicle is following (going behind) which vehicle in 5 lanes (one direction). For example, In this table, 3Ws are following 120 2Ws and 90 cars. In other table it shows total number of vehicles present...
3. Exercise on standard distribution

Hello, Suppose I want to calculate the probability for a user to pass from a basic to a premium account within the end of Q1 (i.e. end of march). I know that this is distributed with mean=50 days and st.dev=10 days, then the probability that a user pass to a premium account within the end of...
4. What will be the Probability?

If a treatment for cancer has 90% success rate, the remaining 10% die. If two patients come for treatment, what is the probability that one will die?
5. comparing groups and the significance of two outcomes in each group

Hi, It's been 10 years since I picked up a stats book and wondering what's the best tool for the job. Given 2 systems, 3 categories in each system (better, same, worse) and for each category two outcomes (a win or loss). Is there a statistical significance of a win or loss between the 3...
6. Using probit model

Could anybody explain to me how to work with a model based on probit analysis? I have for example a model like this: Z=-2,067-2,324x+3,213y+1,782v (x, y, v will be replaced by measured values) and I would like to get a probability. I know I have to use several steps but i have no idea which...
7. Selection probability + time variable?

Greetings statisticians, I seek advice regarding a probability of selection. Here is the scenario: I, living in the US, have a music collection totaling 1000 CDs. A friend, living in Southeast Asia, has a collection totaling 2000 CDs. Given that we have similar musical interests yet live in...
8. Classical Probability

Greetings from new comer! Here is my question I could not figure it out by myself: There are two types of bags H and R in a single box (black box and you can't see through!). The number of the two types of bags are more than 10,000 that can be treated as infinite. In bag type H there are red...