So..... favourite #2 daughter in grade 10 asked for math assignment help and i have no idea, but am now invested in finding out before she does...

She has to build a quadratic equation for the following data showing the moons illumination % per day in January.

My very limited skills fell apart as the data graphs to a sinusoidal wave and not a parabola, and i can not determine a second difference in the y data.

can it be done? show your working please.... apologies if this is a chump post..

Day of the month - % Illumination

1 30

2 39

3 48

4 58

5 67

6 76

7 84

8 90

9 96

10 99

11 100

12 98

13 94

14 87

15 78

16 68

17 56

18 45

19 34

20 24

21 16

22 9

23 4

24 1

25 0

26 1

27 4

28 9

29 15

30 22

31 31

salty