利用随机模拟的方法可以估计图中由曲线

与两直线
x=2及
y=0所围成的阴影部分的面积
S:①先产生两组0~1的均匀随机数,
a=
RAND( ),
b=
RAND( );② 做变换,令
x=2
a,
y=2
b;③产生
N个点(
x,
y),并统计落在阴影内的点(
x,
y)的个数

,已知某同学用计算机做模拟试验结果,选取了以下20组数据(如图所示),则据此可估计
S的值为____.
x
| y
| y-0.5*x*x
|
0.441414481
| 1.849136261
| 1.751712889
|
1.836710045
| 0.508951247
| -1.177800647
|
1.389538592
| 0.999398689
| 0.033989941
|
0.745446842
| 1.542498362
| 1.264652865
|
0.981548556
| 1.928476536
| 1.446757752
|
1.87036015
| 1.287100762
| -0.462022784
|
1.20252176
| 1.271691664
| 0.548662372
|
1.931929493
| 0.920911487
| -0.945264297
|
0.450507939
| 1.561663263
| 1.460184562
|
1.356178263
| 1.856227093
| 0.936617353
|
0.408489063
| 1.564834147
| 1.481402489
|
0.163980707
| 0.135034106
| 0.121589269
|
1.868152447
| 0.350326824
| -1.394669959
|
0.252753469
| 1.287326597
| 1.255384439
|
1.253648606
| 1.872701968
| 1.086884555
|
0.679831952
| 0.140283887
| -0.090801854
|
1.544339084
| 0.804655288
| -0.387836316
|
1.563089931
| 0.872844524
| -0.348780542
|
1.17458008
| 0.867440167
| 0.177620985
|
1.057219794
| 1.791271879
| 1.232415032
|
