We have to identify the sampling technique used in each case:
6) Using a random table corresponds to a simple random sampling.
7) We can consider the top 10 students as a strata of the class. As the sample only includes this strata, it can be considered a stratified sampling.
8) In this case, the sampling is initially random but following a deterministic interval (in this case, position in the line). This correspond to a sytematic sampling.
9) In this case, the hospitals are the clusters. Each cluster is then surveyed completely.
As the researcher surveyed all individuals within each hospital, this is a cluster sampling.
10) The 10 barangays are selected randomly from the population without any special criteria, so it is a simple random sampling.