Astatewide sample survey is to be made. first, the state is subdivided into counties. seven counties are selected at random and further sampling is concentrated on these seven counties. what type of sampling is this?

Cluster sampling

Explanation:

In cluster sampling the population is organized in a homogeneous manner from which a sample is chosen. The homogeneity of the cluster is selected according to a criteria.

Here, the states are the population which have been divided into clusters of counties. The counties are selected at random from which the sampling is done.

Hence, here cluster sampling has been used.

d - failures.

the only attempted british colony in north america before 1600 was roanoke, virginia, which was a total failure. england claimed several areas, including newfoundland, but made no sustainable attempts to colonize them before 1600.