We have 10 buttons in total out of which 5 are blue, therefore, the chance of picking up a blue button is 5 out of 10. The chance of picking a specific colour of button from the pile depends upon the number of the particular colour in the pile.
If I pick up a button from the pile while keeping my eyes closed then how much do you think will be the chance of picking up a red button out of 10? [Correct answer: 3/10]