Answer:
The symbol Σ (sigma) is generally used to denote a sum of multiple terms.
Step-by-step explanation:
In number 1 you just add the value of X1, X2, X3 and X4 to get the sum.
Σ X = X1 + X2 + X3 + X4
Σ X = 4 + 2 + 5 + 1 = 12
then do the same in number 2 to 3
In number 4, Σ XY you should multiply first Xand Y before you add them.
Σ XY = X1Y1 + X2Y2 + X3Y3 + X4Y4
Σ XY = (4)(2) + (2)(1) + (5)(0) + (1)(2) = 12
same in number 5 to 7
In number 8, Σ (X + Y)
Σ (X + Y) = (X1+Y1) + (X2+Y2) + (X3+Y3) + (X4+Y4)
Σ (X + Y) = (4+2) + (2+1) + (5+0) + (1+2) = 17
now you can do the rest good luck!
