How To Calculate Probability
By: Jared Evan
Chances are you need help to calculate probability. Statistical probability can be a tricky
subject. But with a little help, the odds are high that you'll be able to find probability
answers quickly and easily.
Probability is the likelihood of an event occurring divided by the number of possible
outcomes. That may sound a little confusing, so let's break it down into simpler terms
with an example.
Say you have a quarter. If you flip it in the air, what's the likelihood that it will land on
heads? One side of the coin is heads and the other is tails. So the total number of
outcomes is two, heads or tails. The likelihood of it landing on heads is one, because
there is only one heads side. So you just figured out the probability of a coin landing on
heads is 1:2, or half of the time.
What if you flipped the coin and it has landed on tails 8 times in a row? What is the
probability of the coin landing on heads in the next flip? The answer is still 1:2. Because
each event is unique, it doesn't matter how many times it lands on tails, the probability of
it being heads is still the same.
While the basic rules of probability are always the same, the math gets a little trickier
when the numbers get bigger. Consider a deck of cards. A deck contains 52 cards, with 4
suits: clubs, hearts, diamonds and spades. There are 13 cards in each suit.
Shuffle the deck and pick one card out. What is the probability that the card you chose is
a club? In order to calculate probability, you need to know how often an event can occur
and how many possible outcomes exist. Since there is a total number of 52 cards in the
deck that is the total number of outcomes. The likelihood of the card you picked being a
club depends on the number of clubs in the deck. We know that there are 13 clubs in a
deck. Your answer is 13:52, which reduces to a 1 in 4 chance of choosing a club. If you
put that card back in the deck and reshuffle, you know your odds will remain the same,
just like flipping the coin.Shuffle the deck and pick one card out. What is the probability that the card you chose is
a club? In order to calculate probability, you need to know how often an event can occur
and how many possible outcomes exist. Since there is a total number of 52 cards in the
deck that is the total number of outcomes. The likelihood of the card you picked being a
club depends on the number of clubs in the deck. We know that there are 13 clubs in a
deck. Your answer is 13:52, which reduces to a 1 in 4 chance of choosing a club. If you
put that card back in the deck and reshuffle, you know your odds will remain the same,
just like flipping the coin.
Now say you draw a club and put that card aside, instead of reshuffling it into the deck.
What is the probability of drawing another club? In this scenario, the probability is going
to change because our data has changed. Instead of there being 13 clubs left in the deck,
there are now only 12. The total number of outcomes has also changed, dropping to 51.
To calculate the probability, take the likelihood of drawing a club, 12, over the total
number of outcomes, 51. Your answer is 12:51. That answer can't be reduced, because
you can't divide 51 by 12.Here are some simple steps one can use when talking to your baby.
Calculating probability is a simple matter of knowing the variables. Always check your
final answer to see if it can be reduced by dividing the numbers into each other, or by a
common factor.