Question

Every summer, Britney goes on a week-long canoe trip with her childhood camp friends. After the trip, she usually purchases some oars from the destination city. Her collection of oars is organized by year and type of wood. Spruce wood Ash wood 2010 20 12 2011 19 9 2012 15 22 What is the probability that a randomly selected oar was purchased in 2011 or was not made from ash wood? Simplify any fractions.

Answer 1

First, we can find the total number of outcomes by adding all the numbers on the table:

$n=20+19+15+12+9+22=97$

then, let A be the event "a randomly selected oar was purchased in 2011" and let B be the event "a randomly selected oar was not made from ash wood". Then, their probabilities are:

$\begin{gathered} P(A)=\frac{28}{97} \\ P(B)=\frac{54}{97} \end{gathered}$

then, the probability that event A or B happen is:

$P(A\cup B)=\frac{28}{97}+\frac{54}{97}=\frac{82}{97}$

therefore, the probability is 87/97