Answer:
495 combinations of 4 students can be selected.
Step-by-step explanation:
The order of the students in the sample is not important. So we use the combinations formula to solve this question.
Combinations formula:
is the number of different combinations of x objects from a set of n elements, given by the following formula.

How many combination of random samples of 4 students can be selected?
4 from a set of 12. So

495 combinations of 4 students can be selected.
Answer:
60
Step-by-step explanation:
5 x 12
60
Answer:
6 cm
Step-by-step explanation:
If you use Tangent-secant product (chapter reference), AB/AC = AD/AB so 4/2 = AD/4. AD = 8, CD = AD - AC = 8 - 2 = 6 cm.
Let n be the first even integer, and n+2 will be the second even integer. (Why? Think 2 and 4, 2+2=4. This is the case for every consecutive even integers).
n + 3(n+2) = 54
n + 3n + 6 = 54
4n = 48
n = 12, n+2 = 14