Question
There are 50 families in a village.
C = {families who own a car}
B = {families who own a bicycle}
23 families own a car.
10 families own a car and a bicycle.
6 families own no cars and no bicycles.
(a) Complete the Venn diagram.
(b) Find n(C∪B).
▶️ Answer/Explanation
Solution
Ans: (a) Venn diagram: Only car = 13, Both = 10, Only bicycle = 21, Neither = 6
(b) 44
(a) Only car = 23 – 10 = 13. Total accounted for = 13 + 10 + 6 = 29, so only bicycle = 50 – 29 = 21.
(b) n(C∪B) = Total – neither = 50 – 6 = 44, or 13 + 10 + 21 = 44.
Question
The Venn diagram shows elements of sets ξ, P and Q. Complete the statements.
(a) Write down the elements of set P.
(b) Find n(P ∪ Q).
▶️ Answer/Explanation
Solution
(a) {a, b, c, d}
These are the elements shown inside circle P.
(b) 6
Counting all elements in P or Q gives 6 elements.