Question

Tickets numbered from 1 to 20 are mixed up and a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 7?

Answer 1

Sample space, n(S) = 20 

Number of events of getting a multiples of 3 or 7 on the drawn ticket,

n(E) = 8 {3,6,9,12,15,18,7,14}

∴ P(E) = \(\frac{n(E)}{n(S)}\) = \(\frac{8}{20}\) = \(\frac{2}5\)