Answer:
Step-by-step explanation:
Simplifying
x2 + -9x = 4x + -4
Reorder the terms:
-9x + x2 = 4x + -4
Reorder the terms:
-9x + x2 = -4 + 4x
Solving
-9x + x2 = -4 + 4x
Solving for variable 'x'.
Reorder the terms:
4 + -9x + -4x + x2 = -4 + 4x + 4 + -4x
Combine like terms: -9x + -4x = -13x
4 + -13x + x2 = -4 + 4x + 4 + -4x
Reorder the terms:
4 + -13x + x2 = -4 + 4 + 4x + -4x
Combine like terms: -4 + 4 = 0
4 + -13x + x2 = 0 + 4x + -4x
4 + -13x + x2 = 4x + -4x
Combine like terms: 4x + -4x = 0
4 + -13x + x2 = 0
Begin completing the square.
Move the constant term to the right:
Add '-4' to each side of the equation.
4 + -13x + -4 + x2 = 0 + -4
Reorder the terms:
4 + -4 + -13x + x2 = 0 + -4
Combine like terms: 4 + -4 = 0
0 + -13x + x2 = 0 + -4
-13x + x2 = 0 + -4
Combine like terms: 0 + -4 = -4
-13x + x2 = -4
The x term is -13x. Take half its coefficient (-6.5).
Square it (42.25) and add it to both sides.
Add '42.25' to each side of the equation.
-13x + 42.25 + x2 = -4 + 42.25
Reorder the terms:
42.25 + -13x + x2 = -4 + 42.25
Combine like terms: -4 + 42.25 = 38.25
42.25 + -13x + x2 = 38.25
Factor a perfect square on the left side:
(x + -6.5)(x + -6.5) = 38.25
Calculate the square root of the right side: 6.184658438
Break this problem into two subproblems by setting
(x + -6.5) equal to 6.184658438 and -6.184658438.
is calculated from the sample, and used as an estimate for the population variance. Thus, it can be said that it represents both 362 and 5530 customers, and the correct option is D.
