Answer: 5
Step-by-step explanation:
Let R be the event that players threw right-handed.
Let O be the event that players were over 30 years old.
Given: Total players = 25
n(R) = 17 , n(O) = 12 , n(R and O)=9
According to the probability formula,
n(R or O) = n(R)+n(O)-n(R and O)
⇒ n(R or O) =17+12-9
⇒ n(R or O) = 20
Now , n(neither R nor O) = Total - n(R or O)
= 25-20
=5
Hence, the number of players on the team neither threw right-handed nor were over 30 years old = 5
