ϰ⼰
һʽ
ЧӦ ѡ
1ݳʽȷijʼΪ400ЧشΪ0.8ôʵӦΪ
A 320 B 800 C 400 D 480 𰸣B
2֪ijЧӦΪ0.8üıҪΪ300 ÷Ϊ
A 375 B 540 C 240 D 360 𰸣C
3ݳʽȷijʼΪ400Ҫ20%ӦΪ
A 256 B 320 C 500 D 625 𰸣D
ѡ
1ijԭУ A ԭ B Ԫ֪ C Ԫ D ȡԭ 𰸣ABC
2ӰУ A С B C 巽 D ˮƽ 𰸣ABCD
3ʵʩУ A B ǩ C ȡ D жϳȡ 𰸣ABC ġ
1ȷ 2Ԥ巽ķ
塢
1ijƶƽʱ䣬ȫ98¸ҵĹ
ѡ8ˣʱֱΪ4.25.17.93.85.34.65.14.1λ֣95%ŶȹƸҵƽʱ䣨ϵɺԣ
1n?Y?y??yi?5.0125ni?1s21.65278v(y)?(1?f)?(1?)?0.1897n898s(y)?0.43565.0125?2.36?0.4356(3.98,6.04)
2ij10000óķƸˮüѡ100y=12.5s2=12.52Ƹþˮ95%䡣ҪƵ20%Ӧٻ
1ƽˮ䣺
??y?12.5Ys212.52v(y)?(1?f)?(1?0.01)?0.1239n100s(y)?0.3512.5?1.96?0.35(11.81,13.19)ˮ95%䣺11811319
2
n0?(u?S21.96?12.522)?()?96.35 rY0.2?12.5n?n0?95.43?96 n01?N3. ijزüʳIJԪΪũıϵΪ
ʳ ϵ 0.38 0.39 0.44
ҪϸĿŶΪ95%4%ҪȡٻһʳIJ侫Ƕ٣ 1
t2c2n?2
r ʳ 347 366 465 Ҫȡ465 2
1?r?1?cn?1?0.38465?0.98
4. һüȡ250ţ50ŵݳִ95%Ŷȹдı֪ݹ1000ţĽкα仯ҪƵľ1%ٳȡŵ
p?a50??0.2 n250v(p)?pq?0.000643n?1s(p)?0.025 d?1.96?0.025?0.05
дı95%䣺0.150.25 ֪ݹ1000ţдı95%䣺0.160.24
uPQn0??2?6147
d2

