In a class of 50 students, 33
passed the mathematics test and 31 passed the language test. What is the probability that a
randomly selected student failed in the language test?
In questions of this type, it is
important that we’re able to select the relevant information. We are only interested in what
happened in the language test. This means that the fact we are
told that 33 students passed the mathematics test is irrelevant. We are told that there are 50
students in total. Of these, 31 passed the language
test. Since 50 minus 31 is equal to 19,
we know that 19 students failed the language test. And it is the probability of this
event that we are trying to calculate.
We know that the probability of an
event can be written as a fraction. It is the number of favorable
outcomes divided by the total number of possible outcomes. The probability that a randomly
selected student failed in the language test is therefore equal to 19 over 50, which
could also be written as the decimal 0.38 or 38 percent.