Probability is the chance of an event occurring. For example, when you toss a coin, you can only get two results. It will be either heads or tails. Hence the chances for a coin to land as a head is 1/2 and likewise, the chances of the coin to land as a tail is also 1/2.

In other words, probability is nothing but:

Probability = the number of ways it can occur / total number of outcomes

For example, you have 5 red pens, and 2 blue pens in your bag. Suppose you take a pen without looking into the bag, what is the probability that you will pick a blue pen?

Now you have 5 red pens and 2 blue pens. The chances of you picking a blue pen is 2 from a total of 7 pens.

Hence the probability here is 5 / 7.

Remember, probability will not give you an exact result, but is only an indicator of what the chances are that you have to pick the blue pen.

Let’s say we toss a coin 10 times and work out how many tails will come up.

According to the formula, the probability is 5/10 = ½ or 5 times that you can expect a tail. But in reality, you can either get 10 out of 10 times, if you are really lucky or just get tails 4 times.

Example 1

There are 6 balls in a bag, 3 are green, 2 are white and 1 is yellow. What is the probability of picking a white one?

To calculate the probability, let’s use the formula:

Probability = number of ways it can occur / total number of outcomes

Probability = 2/6 = 1/3

So, for every 3 chance, you might pick a white ball.

Example 2

Let’s assume you have a bag full of chocolates in various colors including red, green, yellow and white. Tony picked out a hundred chocolates and got the following results:

Number of red chocolates – 20
Number of yellow chocolates – 10
Number of white chocolates – 30
Number of green chocolates – 40
Now what is the probability that Tony has to pick a green chocolate?
For every 100 chocolates picked, the chances of picking a green chocolate here is 40 / 100 = 0.4