Question

In a class of 35 students, 5 are freshmen, 8 are sophomores, 9 are juniors and 13 are seniors. If 1 student is randomly selected, what is the probability the student is a junior

Answer 1

`\displaystyle(9)/(35)` or 25.71%.

Probability is the likelihood of an event occurring. The desired outcomes are known as successful outcomes. In this scenario, the successful outcomes are when a junior is selected. The sample size is the total number of students.

Probability as a Fraction

Simple probability (the probability of 1 event) can easily be found as a fraction. For the fraction, the number of successful outcomes should be the numerator and the sample size is the denominator.

This means that the probability of selecting a junior is
`\displaystyle(9)/(35)`.

Probability as a Percentage

In this case, it is easiest to first find the probability as a fraction, but we can then convert it to a percentage if desired.

To convert to the fraction divide the numerator and denominator (I'm rounding to 4 decimal places).

• 9/35 = 0.2571

Then, multiply this decimal by 100, which is the equivalent of moving the decimal point 2 digits to the left.

• 0.2571 * 100 = 25.71%