There are a total of 33 students in the class (21+12=33). There are 12 boys in the class so the chance of drawing a boys name would be 12/33 which reduces to 4/11. This means you will draw a boys name 4 times for every 11 draws. To find the percent probability, just divide...
4/11 =.3636
multiply by 100 to convert to a percentage ( move decimal to the right 2 places).
.3636 = 36.36%
There is a 36.36% chance that a boys name is drawn.
