Question

one ticket is drawn at random from a set of 20 digit number from 1 to 20 what is the probability that a number of the ticket drawn is divisible by 2 or 3​

Answer 1

let S be the sample space
= 1 2 3 4..........20
n (s)=20
event A = no. divisible by 2
A=2 4 6 8 10 12 14 16 18 20
n (A)=10
p (A) =n (A)/n(s)=10/20
probability of divisible by 2 is 1/2

event B = no. divisible by 3
B=3 6 9 12 15 18
n (B) =6
p (B)=n (B)/n (s)=6/20
and probability of divisible by 3is 3/10

Answer 2

total outcome =20

fav outcomes=lcm(2,3)=6

IE, 6,12,18

p(e)=3/20