Answer:
The correct option is;
0.28
Step-by-step explanation:
The given data values are;
x, f(x)
8, 12
12, 40
6, 15
20, 20
Where;
x = The number of flowers in the bouquet
f(x) = The total cost (in dollars)
The equation for linear regression is of the form, Y = a + bX
The formula for the intercept, a, and the slope, b, are;
[tex]b = \dfrac{N\sum XY - \left (\sum X \right )\left (\sum Y \right )}{N\sum X^{2} - \left (\sum X \right )^{2}}[/tex]
[tex]a = \dfrac{\sum Y - b\sum X}{N}[/tex]
Where:
N = 4
∑XY = 1066
∑X = 46
∑Y = 87
∑X² = 644
(∑X)² = 2116
b = (4*1066 - 46*87)/(4*644 - 2116) = 0.5696
a = (87 - 0.5696*46)/4 = 15.1996
The standard deviation of the x- values
[tex]S_X = \sqrt{\dfrac{\sum (x_i - \mu)^2}{N} }[/tex]
[tex]\sum (x_i - \mu)^2}[/tex] = 115
N = 4
Sx =√(115/4)
Sx = 5.36
[tex]S_Y = \sqrt{\dfrac{\sum (y_i - \mu_y)^2}{N} }[/tex]
[tex]\sum (y_i - \mu_y)^2}[/tex] = 476.75
N = 4
Sy =√(476.75/4)
Sy= 10.92
b = r × Sy/Sx
Where:
r = The correlation coefficient
r = b × Sx/Sy = 0.5696*5.36/10.92 = 0.2796 ≈ 0.28
The correct option is 0.28.
