Consider rolling two dice once. Calculate the probability of rolling a sum of 5 or an even sum.

Solution :

Sample space of rolling two dice = 36

Now, Event of sum of 5 = { (1,4) (2,3) (3,2) (4,1) } = 4

\(\implies\) probability of getting sum of 5 is 4/36 = 1/9

Now, Event of even sum = { (1,1) (1,3) (1,5) (2,2) (2,4) (2,6) (3,1) (3,3) (3,5) (4,2) (4,4) (4,6) (5,1) (5,3) (5,5) (6,2) (6,4) (6,6) } = 18

\(\implies\) probability of getting even sum is 18/36 = 1/2

Hence, probability of  getting sum of  5 or even sum = 1/9 + 1/2

= 11/18


Similar Questions

The probability of India winning a test match against the west indies is 1/2 assuming independence from match to match. The probability that in a match series India’s second win occurs at the third test is

The probability that A speaks truth is 4/5 while this probability for B is 3/4. The probability that they contradict each other when asked to speak on a fact is

If A and B are two mutually exclusive events, then

A and B play a game, where each is asked to select a number from 1 to 25. If the two numbers match, both of them win a prize. The probability that they will not win a prize in a single trial is

At a telephone enquiry system, the number of phone calls regarding relevant enquiry follow. Poisson distribution with an average of 5 phone calls during 10 min time intervals. The probability that there is almost one phone call during a 10 min time period is

Leave a Comment

Your email address will not be published.