Average score in the first 7 tests is 82. How much do you need to score to get an average of 85?

X+X+X+X+X+X+X/7=82

X+X+X+X+X+X+X+X/8=85

X+X+X+X+X+X+X=574

X+X+X+X+X+X+X+X=680

X=106

You need to score 106

Hope this helps :D

The correct answer is D. It is not true that cluster sampling uses randomly selected clusters and samples everyone within each cluster.

Step-by-step explanation:

Cluster sampling is a method of collecting samples and statistical data, by means of which a certain group formed by people, things, events, etc., is taken as a sample, which are not considered individually but as part of a whole, which is in turn a proportional representation of the universality of samples available in the field.

Now, since this type of sampling allows to embrace large groups of sample units, data are not always obtained from all the components of the cluster, but from those necessary to be able to quantify the desired statistics.