Answer : We know that,

If odds in favor of the occurrence an event are a:b, then the probability of an event to

occur  similarly, if odds are not in the favor of the occurrence an event are a:b, then the probability of not occurrence of the event

is a/a+b

We also know that,

Probability of occurring = 1 – the probability of not occurring

7/4+3
Conclusion: Probability that the event occurs is 7/11

Given a = 4 and b = 7 Probability of occurrence