THE probability is the area of Mathematics that studies the chances of an event occurring. Although it is introduced in elementary school and deepened in high school, this content requires a very advanced knowledge, so it is possible that some mistakes are made in solving their Exercises.
To help high school students, we've listed the threemistakesmorecommitted in calculating probability. Thus, it is possible to prepare well for school evaluations and even for Enem and entrance exams.
problem interpretation
This error doesn't just happen in exercises of odds. In most cases, the student knows how to solve the problems, but he ends up not interpreting them correctly and, therefore, he can get the solution wrong.
There is also the case, no less frequent, of confusion as to the type of probability which should be used to solve a given problem. In some situations, for example, you should use the conditional probability, but the exercise text does not always make this clear. As this interpretation must come from the student, he must be prepared for all these cases.
As an example of a misinterpretation, see the following case:
A die was cast only once, and the result obtained on its upper face observed. Which probability of not finding a number less than or equal to 2?
This is a very simple problem of probability, which can be solved in two different ways:
a) Define the event "exit 1 or 2", calculate your probability and subtract that result from 1.
b) Define the event "exit 3, 4, 5 or 6" and calculate your probability.
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Generally, the student chooses the first path and can forget to subtract the probability to get out 1 or 2 of 1. This subtraction is mandatory as we are interested in the probability of no exit 1 or 2.
Combinatorial Analysis Error
Some experimentsrandom, as in the example above, allow for easy and fast counting of elements, but others require the use of the combinatorial analysis for this. Therefore, its good use is essential for many exercises of probability in which it is necessary to find the number of elements of the sample space It's from event.
In order not to make mistakes in these calculations, it is essential to know the following topics well:
1. Fundamental principle of counting;
2. simple combination;
3. Arrangement; and
4. Permutation.
Failures in basic math
You mistakesmorecommitted throughout Mathematics, no doubt, are related to mathbasic. There are those who make mistakes by simple lack of attention, for example, confusing operations, and there are still those who really don't know how to perform the basic calculations due to some flaw in the process of teaching-learning.
In both cases, we advise you to pay close attention to each calculation and each line of the solution to the problem. For the second case, we advise you to dedicate a lot of study time to the mathbasic: operations, equations, functions, numerical sets, algebraic expressions and every kind of simplification that is possible in mathematics, potency properties it's from roots etc.
By Luiz Paulo Moreira
Graduated in Mathematics
Would you like to reference this text in a school or academic work? Look:
SILVA, Luiz Paulo Moreira. "The Three Most Made Mistakes in Probability Calculation"; Brazil School. Available in: https://brasilescola.uol.com.br/matematica/os-tres-erros-mais-cometidos-no-calculo-probabilidade.htm. Accessed on June 28, 2021.
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