In: Operations Management
The following gives the number of accidents that occurred on Florida State Highway 101 during the last 4 months: Month Jan Feb Mar Apr Number of Accidents 25 45 70 105 Using the least-squares regressionLOADING... method, the trend equation for forecasting is (round your responses to two decimal places): ModifyingAbove y with caret = nothing + nothingx
The Accident data
Month |
Period (x) |
Number of Accidents (y) |
x*y |
x^2 |
Jan |
1 |
25 |
25 |
1 |
Feb |
2 |
45 |
90 |
4 |
Mar |
3 |
70 |
210 |
9 |
Apr |
4 |
105 |
420 |
16 |
10 |
245 |
745 |
30 |
We know that, using trend equation,
y = a + b*x
where y is number of accidents
x is the concerned period
a = {(∑y)*(∑x2) – (∑x)*(∑xy)} / {(n)*(∑x2) – (∑x)*(∑x)}
b = {(n)*(∑xy) – (∑x)*(∑y)} / {(n)*(∑x2) – (∑x)*(∑x)}
Here,
∑x = 10
∑y = 245
∑x*y = 745
∑x2 = 30
n = number of observations = 4
Putting all the values in a and b
a = {(245*30) – (10 * 745)}/{(4*30) – (10*10)}
= (7350 – 7450)/(120 – 100)
= -100/20
= -5
a = -5
b = {(4*745) – (10*245)}/{(4*30) – (10*10)}
= (2980 – 2450)/(120 – 100)
= 530/20
= 26.5
b = 26.5
Hence, y = 26.5*x – 5
Caret = 26.5*x – 5
.
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