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.
1.5 year is also 17 months. so 4060-3125=935 which equals 10 months, then 935÷10=93.5 which gives us the monthly dues. Then 93.5×7=654.5 which gives us the total of monthly dues for 7 months without the intuition fee. Then 3125-654.5=2470.5 that gives us the intuition fee.
