Question

Two unbiased dice are rolled once. What is the probability of getting a sum equal to 7?

Answer 1

Hint: Probability is a measure of the likelihood of an event to occur. It can be mathematically represented as $\dfrac{{No.{\text{ }}of{\text{ }}favourable{\text{ }}outcomes}}{{total{\text{ }}number{\text{ }}of{\text{ }}outcomes}}$.

Complete step-by-step answer:

Let Dice 1 be D1 and Dice 2 be D2
Now combinations which will result to favourable outcome i.e. Sum of D1 and D2 is 7 will be

So, number of favourable outcome when sum of D1 and D2 are 6
and total number of outcomes will be $6 \times 6 = 36$
So, we know that probability of an event = $\dfrac{{No.{\text{ }}of{\text{ }}favourable{\text{ }}outcomes}}{{total{\text{ }}number{\text{ }}of{\text{ }}outcomes}}$
So, the probability of sum of two dices to be 7 = $\dfrac{6}{{36}} = \dfrac{1}{6}$

Note: In these types of questions where the number of favourable outcomes are countable draw a sheet of all the possible outcomes and then divide it with the total number of outcomes to get probability of an event.