Question 1193669
two sample proportion 95% half-interval is z*SE
SE:  start with group 1 SE which is sqrt(0.6*0.4/100) or 0.0490, and group 2 SE which is the same
the SE is sqrt(0.0490^2+0.0490^2)=0.0693
z*SE=1.96*0.0693=0.1358
the actual 95%CI is the difference +/- SE which is (0.0642, 0.3358). We are looking at the difference in proportion of survival between 1 and 2.
This is consistent with the highly significant difference.