Question 1149747
20% walkers, or 1/5,  is a ratio of [ 1 walker ] / [ 4 non-walkers ]
Now double the number of walkers
[ 2 walkers ] / [ 4 non-walkers ]
As a fraction of all the students, this is:
{{{ 2/6 = 1/3 }}}
1/3 of the students are now walkers