Question

A teacher uses the copy machine one out offour days. He/she buys coffee at the coffeeshop one out of eight days. Assuming using thecopy machine and buying coffee at the coffeeshop are independent events, what is theprobability that the teacher uses the copymachine and buys coffee tomorrow? Give youranswer as an exact fraction and reduce thefraction as much as possible.

Answer 1

SOLUTION

From this statement: A teacher uses the copy machine one out of four days, it means that the probability of using a copy machine is

$\frac{1}{4}$

And from this: He/she buys coffee at the coffee shop one out of eight days. It means the probability of buying a coffee at a coffee shop is

$\frac{1}{8}$

Hence, the probability that the teacher uses the copy machine and buys coffee tomorrow means we multiply both probabilities.

We have

$\begin{gathered} \frac{1}{4}\times\frac{1}{8} \\ =\frac{1}{32} \end{gathered}$

Hence the answer is

$\frac{1}{32}$