Question

20 cards numbered 1 2 3 ...... 20 are put in a box and mixed throughly shashi draws a cards from the box find the probability that the no on the cards is
Odd , even, prime , divisible by 3 , divisible by 3 and 2

Answer 1

n(s) =20

A=If it's odd number than

{1,3,5,7,9,11,13,15,17,19}

n(a)=10.

P(A) =n(A) /n(S)

10/20

2.

B=if the number is even

B ={2,4,6,8,10,12,14,16,18,20}

n(B) =10

P(B)=n(B)/n(S)

10/20

2.

C=if it's a prime number

C={1,2,3,5,7,11,13,17,19}

n(C) =9

P(C) =n(C) /n(S)

9/20.

D=if the number is divisible by 3.

D={3,6,9,12,15,18}

n(D) =6

P(D)=n(D)/n(S)

6/20

2\10

E=if the number is divisible by 3&2.

E={6,12,18}

n(E)=3

P(E)=n(E)/n(S)

3/20.