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A business owner creates the following table of data modeling weekly profit in thousands of dollars.



Weeks Profit (in thousands)

0 −7

1 4

2 14

3 23

4 29

5 35

6 38

7 40

8 41

9 40

10 38

11 34

12 29



Using the given values, write a quadratic model to fit the data where x represents weeks and ŷ represents profit.

ANSWERS-
ŷ = −0.25x2 + 8.65x − 7.1
ŷ = 0.25x2 + 8.65x − 7.1
ŷ = −0.76x2 + 12.07x − 6.99
ŷ = 0.76x2 + 12.07x − 6.99

1 Answer

2 votes

To find the quadratic model that fits the given data, we need to find a quadratic equation of the form ŷ = ax^2 + bx + c, where ŷ represents the predicted profit and x represents the number of weeks.

We can use the given data points to create a system of equations. Let's plug in the values from the table:

Week 0: ŷ = -7

Week 1: ŷ = 4

Week 2: ŷ = 14

Week 3: ŷ = 23

Week 4: ŷ = 29

Week 5: ŷ = 35

Week 6: ŷ = 38

Week 7: ŷ = 40

Week 8: ŷ = 41

Week 9: ŷ = 40

Week 10: ŷ = 38

Week 11: ŷ = 34

Week 12: ŷ = 29

Now we can set up the system of equations:

-7 = a(0)^2 + b(0) + c ---> c = -7

4 = a(1)^2 + b(1) + c ---> a + b + c = 4

14 = a(2)^2 + b(2) + c ---> 4a + 2b + c = 14

23 = a(3)^2 + b(3) + c ---> 9a + 3b + c = 23

29 = a(4)^2 + b(4) + c ---> 16a + 4b + c = 29

35 = a(5)^2 + b(5) + c ---> 25a + 5b + c = 35

38 = a(6)^2 + b(6) + c ---> 36a + 6b + c = 38

40 = a(7)^2 + b(7) + c ---> 49a + 7b + c = 40

41 = a(8)^2 + b(8) + c ---> 64a + 8b + c = 41

40 = a(9)^2 + b(9) + c ---> 81a + 9b + c = 40

38 = a(10)^2 + b(10) + c ---> 100a + 10b + c = 38

34 = a(11)^2 + b(11) + c ---> 121a + 11b + c = 34

29 = a(12)^2 + b(12) + c ---> 144a + 12b + c = 29

We can solve this system of equations to find the values of a, b, and c.

After solving the system, we get the following values:

a ≈ -0.76

b ≈ 12.07

c ≈ -6.99

Therefore, the quadratic model that fits the given data is:

ŷ = -0.76x^2 + 12.07x - 6.99

Hence, the correct answer is ŷ = -0.76x^2 + 12.07x - 6.99.

answered
User Isobretatel
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