b) If two dice are thrown together, find the probability of getting:
(i) the sum as a prime number.
(ii) a doublet.
Answers
Answer:
(i) 7/18
(ii) 1/6
Step-by-step explanation:
(1,1) (1,2) (1,3) (1,4) (1,5) (1,6)
(2,1) (2,2) (2,3) (2,4) (2,5) (2,6)
(3,1) (3,2) (3,3) (3,4) (3,5) (3,6)
(4,1) (4,2) (4,3) (4,4) (4,5) (4,6)
(5,1) (5,2) (5,3) (5,4) (5,5) (5,6)
(6,1) (6,2) (6,3) (6,4) (6,5) (6,6)
:. n (s) = 6×6
= 36
(i) let A be the event that the sum of the uppermost faces are prime number
A = {(1,2) (1,4) (1,6) (2,1) (2,3) (2,5) (3,2) (3,4) (4,1) (4,3) (5,2) (5,6) (6,1) (6,5)}
n (A) = 14
:. Probability of getting 'A' = n (A) / n (S)
14/36
7/18 ans.
(ii) let B be the event that there are doublet of number.
B = {( 1,1) (2,2) (3,3) (4,4) (5,5) (6,6)}
:. Probability of getting 'B' = n (B) /n (S)
6/36
1/6 ans.