SRS stands for Simple Random Sample. It consists of selecting a subgroup (of 5 students for this case), while each member of the whole population (80 students for this case) has the same probability of being selected.
That could be done by assigning each individual of the population a number, and then randomly generate a set of numbers to select the subgroup.
In this case, we can assign each of the 80 students a number, and generate 5 random numbers. Those 5 random numbers have to be two-digit numbers since we have more than 10 students.
We can assign numbers from 01 to 80 to each student, and select the first 5 pairs of numbers of the randomly generated set of digits found: 05166 29305 77482.
Let's separate the digits in pairs:
05 16 62 93 05 77 48 2.
We can discard the 2 at the end because it has only one digit:
05 16 62 93 05 77 48
The first five students would be the ones labelled with:
05, 16, 62, 93 and 05.
We have 05 twice, so we can delete it and replace it with the sixth pair of numbers (77):
05 16 62 93 77.
One of the selected numbers is 93, which is outside the range. The selected numbers should be lower than 80. Then, we can discard the 93, and replace it with the seventh pair of the randomly generated digits:
05 16 62 77 48.
Now we have the numbers of the 5 selected students after using the given digits to perform a Simple Random Sample.
The numbers of the selected students are 05, 16, 62, 77 and 48.
This is a fair selection since from the set of randomly generated digits, the probability of obtaining a pair of digits forming a number from 01 to 80 is the same for each of the 80 numbers.