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:
12x + 4x + 20
4(3x + x + 5)
4(4x+5)
Step-by-step explanation:
The answer is B because -3.62 is less than -3.5 and greater than -3.8.
Solution
A=4πr2=4·π·82≈804.24772
Approximately = 804.25