Question

14. A bag contains 5 identicalballs which are numbered
1, 2, 4, 5 and 7. Two balls are drawn at random,
one after another and without replacement.
Find the probability that the
(i) numbers obtained on both balls are prime,
(ii) sum of the numbers obtained is odd,
(iii) product of the numbers obtained is greater
than 20
(iv) difference in the numbers obtained is less
than 7,
(v) product of the numbers obtained is divisible
by 9.​

Answer 1

Answer ⤵️

There are 20 balls in a bag.

Odd numbers between 1-20 are {1, 3, 5, 7, 9, 11, 13, 15, 17, 19}=10

The probability of getting 3 odd numbered balls without replacement:

=

20

10

×

19

9

×

18

8

=

6840

720

=0.105