3x - 18 = 42
3x = 42 + 18
3x = 60
x = 60/3
x = 20
Answer:
Stratified Random sampling
Step-by-step explanation:
When a random observations are selected from a number of individual groups in a particular population, the type of sampling technique is called Stratified Random sampling. Stratified Random sampling begins with the partitioning or splitting or a population into subgroups. A number of random selection are then made from each of the subgroups to form a collection of larger samples. This is different from the simple random sampling technique which makes random selection directly from a larger sample or population without prior partitioning of the population. The different grades of students represents the individual stratum from which random selections are made.
Answer:
3/2 x 7/8 = (3×7)/(2×8)=21/16
