Question

The table below shows the data of the new type of virus disease (COVID-19) from 11 March 2020, the day when the first case occurred in our country, until 21 April 2020, when the virus peaked. In response to these data, the number of patients recovering within the same time frame is given. Find a 2nd order polynomial equation (Ŷ = a0 + a1 x + a2 x2) that fits these data. Then calculate the correlation coefficient. Using the parabola equation, find a regression curve for the number of patients recovering based on the number of cases. Also, estimate when the number of cases will end according to these data.

DAILY CASE NUMBER(X)	DAILY HEALING PATIENTS(Y)
0	1
0	0
0	4
0	1
1	12
1	29
2	41
3	93
4	168
9	311
21	277
30	289
37	293
44	343
59	561
75	1196
92	2069
108	1704
131	1815
168	1610
214	2704
277	2148
356	2456
425	2786
501	3013
574	3135
649	3148
725	3892
812	4117
908	4056
1006	4747
1101	5138
1198	4789
1296	4093
1403	4062
1518	4281
1643	4801
1769	4353
1890	3783
2017	3977
2140	4674
2259	4611

Answer 1

Using Excel, Insert Scatter Plot. Right-click on any point on the plot, select Add Trendline. Choose Polynomial with degree 2. Tick Display R-square on chart and Didplay Equation on chart.

Correlation ceofficient = 0.932

Regression curve: y = = -0.002x2 + 5.9641x + 377.88

When will number of cases end, x = 0

y = -0.002*0 + 5.9641*0 + 377.88 = 377.88 ~378

No. of cases will end on when no. healing patiets healing falls to 378