Question 1166257
this is a 2 sample proportion
p1=0.2 
p2=0.05
z=(p1-p2)/sqrt ((phat ((1/n1)+(1/n2))
=0.15/sqrt ((phat)*(1/1000+(1/20000)), where phat is the pooled proportion of 0.057.
z=19.4
This is highly significant, not surprisingly, given the large sample size and the large difference in proportions.