Question

Two unbiased dice are rolled once. What is the probability of getting
(i) a doublet
(ii) a sum equal to 7
ti​

Answer 1

The outcomes are

(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)

Total outcomes =36

i) Probability of getting a doublet =6/36=1/6

ii) Probability of getting a sum equal to 7=6/36=1/6

Answer 2

1)no.of doublets = 6

total no.of outcomes = 36

So the probability of getting a doublet is :

No. Of doublets / total no. of outcomes =6/36=1/6

2)favourable outcomes = 6

totalno. of outcomes = 36

=6/36 = 1/6