Answer:
This type of sample is called a stratified random sample.
Step-by-step explanation:
Stratified random sampling involves dividing a population into sub-groups(strata) based on characteristics, selecting random samples of the same size from each subgroup and finally combining this random samples. Stratified random sampling is usually used for heterogeneous or dissimilar populations. It is accurate than simple random sampling and saves time time since only a smaller sample size is used.