set.seed(123)
n_m = n_f = p1 = p2 = list()
n_m$total   = sample(5:20)
n_m$success = sapply(n_m$total, function(x) rbinom(1, x, .5))

n_f$total   = sample(5:20)
n_f$success = sapply(n_f$total, function(x) rbinom(1, x, .5))


p1$m = n_m$success/n_m$total
p1$f = n_f$success/n_f$total

p2$m = sum(n_m$success)/sum(n_m$total)
p2$f = sum(n_f$success)/sum(n_f$total)


> n_m
$total
 [1]  9 16 10 19 17  5 18 13 20  8 14  7 12  6 15 11

$success
 [1]  3  5  4 13 11  3 10 11 11  5  7  4  5  2 11  8

> n_f
$total
 [1] 16 20  5 11 14  7  8 15  6 13 17 12 18 19 10  9

$success
 [1]  7 12  1  5  9  2  4  6  2  8 11  5 10  7  5  4


> mean(p1$m/p1$f)
[1] 1.293038
> p2$m/p2$f
[1] 1.153061
>