You have 2 drawers, one drawer had 2 red buttons and a battery. The other has a button in it. What is the probability of getting a button?

Step-by-step explanation:

Each drawer has a 50% chance of being chosen. 50% is 1/2

First drawer

There are 2 buttons this draw out of 3 items. The chance of getting a button here is 2/3

But there is only a 50% chance of choosing this drawer so the answer is

1/2 * 2/3 = 1/3

Second draw.

The chance of this draw yielding a button is 100%. But that is only if the draw is chosen.

So 1/2 * 1 = 1/2

The total probability is 1/3 + 1/2 = 2/6 + 3/6 = 5/6

The probability of getting a button = 5/6 or 0.8333