Have you ever heard your parents or other adults wishing that they
could win millions of dollars in the state lottery? Experts say that
a person has the same chance of winning the lottery as the chance
of being struck by lightening! Only a few people are hit by lightening
just as only a few people win the multi-million dollar prize in the
lottery. These are two examples of probability and two examples of
very unlikely events. An unlikely event is one that probably won't
happen. See how close the word "probably" (which you already know)
is to "probability"?
Let's pretend that you are taking a walk in the park along a paved
trail and you reach a fork in the path. You can take the path on the
left side or you can take the path on the right side. It's up to you
to decide and you don't know what is ahead in either direction. You
have no preference as to which way to turn. Then we could say that
you have an equal chance of turning left or turning right. This means
that the probability, or chance, of turning left or turning right
are the same because there is nothing to influence the choice.
Let's skip ahead to your senior year in high school when you are
ready to go to college. You like two schools with about the same costs
to attend. You receive a scholarship for $10,000 to attend one of
the schools and no scholarship from the other. What is the probability
of attending each school? It is very likely that you will attend the
school that offered you the scholarship. Then the probability of attending
that school is higher than attending the school without the scholarship.
Probability is all around us and it does influence our lives every
day. Before the measles vaccine was invented, most children became
sick with measles when they were in elementary school. Back then the
probability of getting measles was high. Since so many children would
get sick, researchers decided to look for a vaccine. Now if children
get vaccinated for measles, the probability of getting measles is
very low. Working at preventing diseases that have a high probability
of making people sick is one example of how probability influences
Weather forecasts are another way we use probability every day. Do
you ever see the forecast that says 80% chance of showers for tomorrow?
That means that in the past, 8 days out of 10 that had weather like
today were followed by showers. That's a high probability and you
had better bring your umbrella.
What do you think the highest probability is? Is that something
you can figure out? Probably! The highest probability is 100% which
means the event will happen for sure. Sometimes the weather forecast
is simply it will rain tomorrow and it does. Sometimes such a great
storm is coming that the weather forecaster can say for sure that
it will rain, there is a 100% chance of rain.
What is the lowest probability? The lowest probability is 0%, there
is no chance of the event happening. If you are grounded, what is
the probability of going to the basketball game? Most likely 0%.
Human beings make decisions all the time; sometimes the decisions
are simple and other times they are complicated and change the rest
of our lives. Everyone who thinks and plans for their future uses
probability - deciding what are the chances of - in the planning process.
Can you think of some ways that probability has changed your decisions?