Question

A box contains $20$ cards marked with numbers $1$ to $20$. One card is drawn at random. Event A is the number on the card which is multiple of $5$. Write S, n(S), A and n(A).

Answer 1

Event A is card containing $5,10,15$ and $20$.

S is 20 cards

Number of elements in sample space is 20

$n\left(S\right)=20$

$n\left(A\right)=4$