Ram put some buttons on the table. There were 4 blue, 7 red, 3 black and 6 white buttons in all. All of a sudden, a cat jumped on the table and knocked out one
button on the floor. What is the probability that the button on the floor is blue?
Probability = Number of blue buttons on the table / Total number of buttons on the
= 4/20 … [divide both numerator and denominator by 4]