What is the formula of probability?

Number of possible outcome / Number of total outcome

(number of elements in set A/number of times event A can occur) divided by (number of elements in the Universal set)

Rule for addition- P(AuB)=P(A)+P(B)-P(AnB)

Probability of event 'A' is equal to (Number of Event A occurred) divided by (Total Number of Events occurred in Sample Space):

P(A) = n(A)/n(S); where 'A' is Event 'A' Occurred and 'S' is Total Number of Events in Sample Space

Probability of an event = (number of favourable outcomes) / (total number of outcomes)

Hi Rusty,

Probability = Number of favourable Outcomes / Total Number of Outcomes

p (A) = f / N

You need to start by finding the probability of a single outcome. Then find the total number of outcomes that can occur. Finally divide the number of events by the number of possible outcomes.

Probability = (Number of a Favourable outcome) / (Total number of outcomes) 

The formula to find probability is

Probability= (Favourable cases / total cases) x100

Hi Rusty! Due to probability relating to the likelihood of an event occuring, the formula is as followed. It is important to note that probability can be displayed as either a fraction or a decimal.

Probability = the number of times the desired outcome was achieved / the total number of outcomes

Hope this helped!

number of objects in interest / total number of objects

P = n (E) / n (S)

P - Probability

E - Event

S - Sample space

Probability of an event = (number of favourable outcomes) / (total number of outcomes)

Probability = (Number of a Favourable outcome) / (Total number of outcomes) P = n (E) / n (S) Where P is the probability, E is the event and S is the sample space.

There are different formulae for probability depending on situations. If two events A and B are independent (probability of one event does not affect probability of the other) then P(A and B happening together) = P(A) * P(B). If A and B are dependent then the formula becomes: P(A and B happening together) = P(A) * P(B|A). B|A means probability of B given A has already happened. Next comes mutually exclusive. If A and B cannot happen at the same time then P(A or B happening) = P(A) + P(B). If A and B are mutually inclusive that means they can happen at the same time then P(A and B happening) = P(A) * P(B). I mentioned P(B|A) above. This is conditional probability. Probability of 2nd happening given 1st already has happened. And so P(B|A) = P(A and B happening) / P(A happening). There are lots of different formulae and concepts in probability which just makes it so much more interesting.

Probability is the number of ways the outcome can happen over the total possible number of outcomes. For example, if you want to find the probability of receiving an order early from a particular delivery company, you would take the number of times they have delivered early, lets say 10, over the number of deliveries in total, lets say 100. Hence the probability would be 10/100, which is 1/10, which you could write out as 0.1.