[tex]\displaystyle\frac{9}{35}[/tex] 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.
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 [tex]\displaystyle\frac{9}{35}[/tex].
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).
Then, multiply this decimal by 100, which is the equivalent of moving the decimal point 2 digits to the left.