Question

a bag contains 6 black marbles and 6 white marbles. What is the least number of marbles that you must choose, without looking, to be certain that you have chosen two white marbles?

Answer 1

Given:

Number of black marbles = 6

Number of white number marbles = 6

Both marbles have an equal chance of being selected :

`\begin{gathered} P(\text{black marble) = }\frac{Number\text{ of black marble}}{Total\text{ number of marbles}} \\ =\text{ }(6)/(12) \\ P(\text{white marble) = }(6)/(12) \end{gathered}`

The least number of marbles that must be chosen to be certain that you have chosen 2 white marbles is 8 marbles.