There are 170 patients total and 100 out of 170 are given placebo and 70 are not so there is a 70/170 chance of not getting it but if you want a decimal then you divide the numerator 70 by the denominator 170 which is 0.41176... then you have to move the decimal point over to the right by two places so its 41.1176...% you can also round it to 41.12%
