Bicycle or scooter

Text

In a class $60\%$ of the students have a bicycle, $30\%$ have a scooter, $20\%$ have both. What is the probability that a randomly chosen student has at least one of the two?

Solution

We apply the formula for the union of two events, which subtracts the intersection counted twice: $P(\text{bici}\cup\text{mono}) = P(\text{bici}) + P(\text{mono}) - P(\text{bici}\cap\text{mono}).$ Substituting the data: $P(\text{bici}\cup\text{mono}) = 0,6 + 0,3 - 0,2 = \boxed{0,7 = 70\%}$

Links

Topics: Probabilita
Concepts: Unione di eventi
Skills: Calcolo probabilita
Exercise type: Problema probabilita