gordon is a physical therapist who specializes in pediatric leg injuries. his patients differ in age and…

gordon is a physical therapist who specializes in pediatric leg injuries. his patients differ in age and type of injury.\nwhat is the probability that a randomly selected patient is 13 - 19 years old or suffers from knee pain?\nsimplify any fractions.
Answer
Answer:
$\frac{7}{7}$
Explanation:
Step1: Calculate total number of patients
$3 + 3+4 + 5=15$
Step2: Calculate number of 13 - 19 year - old patients
$4 + 5=9$
Step3: Calculate number of patients with knee pain
$3+4 = 7$
Step4: Calculate number of 13 - 19 year - old patients with knee pain
$4$
Step5: Use the inclusion - exclusion principle
$n(A\cup B)=n(A)+n(B)-n(A\cap B)$ Here, $A$ is the set of 13 - 19 year - old patients and $B$ is the set of patients with knee pain. $n(A\cup B)=9 + 7-4=12$
Step6: Calculate the probability
$P=\frac{12}{15}=\frac{4}{5}$