Contingency Tables and Probability Trees · Try It 1

shows the number of athletes who stretch before exercising and how many had injuries within the past year.
$$\begin{array}{cccc}& \text{Injury in last year}& \text{No injury in last year}& \text{Total}\\ \text{Stretches}& \text{55}& \text{295}& \text{350}\\ \text{Does not stretch}& \text{231}& \text{219}& \text{450}\\ \text{Total}& \text{286}& \text{514}& \text{800}\end{array}$$

(a) What is P(athlete stretches before exercising)?
(b) What is P(athlete stretches before exercising$|$no injury in the last year)?

OpenStax, Introductory Business Statistics 2e · §3.4 Contingency Tables and Probability Trees · Try It 1