Introduction to Probability

Probability is the chance that an event will happen

Suppose we toss a coin, what are the chances that we’ll get a HEAD?

so Probability is :

                                                                        Conditional Probability

Suppose we have 2 coins :

• Unbiased coin : a normal coin having a tail and a head
• Biased coin : a special coin having head on both sides

We randomly choose a coin and toss it.

What is the probability of getting a head : 

1. If we chose the unbiased coin?

2. If we choose the biased coin?

What is the probability of getting a HEAD using both coin?

Suppose we choose a coin at random and toss it, and we get heads, now what is the probability that the coin is UB?

Another way to calculate the same

What we know?

What we have to find?

What other information do we have? :We get ‘heads’ when we toss a coin.

Bayes Theorem :