A group of students measured the time taken between seeing
and hearing another student clashing two pieces of wood
together. The distance from the source of sound to the students
was 250m.

After repeating the experiment 5 times, they obtained the
following timings in seconds: 0.73, 0.78, 0.69, 0.81, 0.77.

Use their measurements to calculate the speed of sound.

Why was it advisable for the students to repeat 5 times?