The expected value is 0.12, standard error given that n = 20 = 0.0727
The expected value is 0.12, standard error given that n = 50 = 0.0460
How to solve for the standard error
The population proportion p=0.12
we have the expected value as well as the standard error as what we have to compute here
when we have n = 20


= 0.0727
Then we have n = 50
using proportion as 0.12

Then n = 0.0460
Hence the standard error given that n = 20 = 0.0727
The standard error given that n = 50 = 0.0460