Answer:
proportional stratified random sampling
Step-by-step explanation:
Based on the information provided within the question it can be said that in this scenario the kind of sampling being used is called proportional stratified random sampling. This type of sampling is when the size of the sample is proportionate to the population size of the strata when compared to the entire population. Which in this case 20 males would be the same as 40% of the entire population while 30 females is proportionate to 60% of the entire population.
50 (sample size) * 0.40 = 20
50 (sample size) * 0.60 = 30