Question

Each letter of the word "thunderstorm" has been written on a separate slip of paper and put into a box. Find the probability of selecting a slip of paper with the letter t on it, then selecting the letter r, with replacement?

Answer 1

SOLUTION

From the question, we want to find the probability of selecting a slip of paper with the letter t on it, then selecting the letter r, with replacement.

This means the probability of selecting t and r.

That is

$P(t)\times P(r)$

There are 12 letters (total outcomes). And there are 2r and 2t.

So probability becomes

$\begin{gathered} \frac{possible\text{ outcome}}{\text{total outcome }} \\ P(t)=\frac{2}{12} \\ P(r)=\frac{2}{12} \\ P(t)\times P(r)=\frac{2}{12}\times\frac{2}{12} \\ =\frac{1}{6}\times\frac{1}{6} \\ =\frac{1}{36} \end{gathered}$

Hence the answer is

$\frac{1}{36}$