There are 28 combinations.
Step-by-step explanation: Initially, each of the seven bins holds one ball, leaving two remaining. If both are placed in the same bin, that offers 7 options. Conversely, if each remaining ball is positioned in different bins, the combination comes down to: 21 + 7 = 28 ways.
This seems to be a title for a worksheet??
Yes, it was a reasonable result
Step-by-step clarification:
He created a scalene triangle.
A scalene triangle has sides and angles that do not measure alike.
surface area = 4 x pi x r^2
diameter is 1, thus radius = 1/2 = 0.5
4 x 3.14 x 0.5^2 = 3.14 square meters