E(X) = 0(0.7) + 1(0.2) + 2(0.1) = 0.2 + 0.2 = 0.4
The expected daily loss due to blackouts = 0.4 * $500 = $200
Var(X) = 0(0.7 - 0.4)^2 + 1(0.2 - 0.4)^2 + 2(0.1 - 0.4)^2 = 0.04 + 0.18 = 0.22
The expected daily variance due to blackouts = 0.22 * $500 = $110
Place value can be used to subtract 4.23 and 2.75 because, in order to subtract, you must line up the whole numbers together, the tenths place together, and the hundredths place together.
Lining them up: Whole= W Tenths place= T Hundredths place= H
W T H
4 . 2 3
- 2 . 7 5
-------------------
1 . 4 8
Product means the result you get after multiplying. So you have to multiply the two numbers. 379*8 = 3032
The exterior angles of a polygon all add to 360, if you need to find an exterior angle when given the number of sides and that all angles are equal you simply do: 360/ number of sides.
When you need to find the exterior angle when given an interior angle, you do: 180- interior angle.
Hope this helps :)