72 sq in times 9 is 648 sq in
That it is that many deviations away from the mean.
We are to select 2 people to sit in first row from 6.
This is a problem of Combinations. We are find permutation of 6 people taken 2 at a time. This can be represented as 6C2.
So, the answer is option B
Here is a picture of each.
Here are the definitions of each:
1. Equilateral- this triangle has side lengths that are all the same (congruent).
2. Isosceles-this triangle has exactly 2 sides that are the same length(congruent).
3. Scalene- this triangle has no sides that are the same length.