Question 333885
If you had 8.5 cm of ribbon, then only {{{8.5/8.5=1}}} student can do the experiment. If you had 17 cm of ribbon, then {{{17/8.5=2}}} students can do the experiment. 



So if you had 570 cm of ribbon, then {{{570/8.5=67.05}}} which means that about 67 students can do the experiment (round down to the nearest whole number).