内容正文:
书书书
18.
!
:
(1)x
!
=70+88+87+85+99+96+987 =89,
s2
!
≈87.4,
x
"
=79+77+85+88+92+91+907 =86,s
2
"
≈
30.3,
#$
x
!
>x
"
,
%!&'()*+,-
.
./
:
!&'01)*(23456"-
;
"&'
01)*23456!78
.
(2)
9
(1)
:;!&'01)*23(45$
89
4
,
<=>?$
89×30×20=53400
@
.
19.
!
:(1)
ABC
,
DEFGH(EIJK(KL
$
73-54=19,
MN
n=570÷19=30.
(2)
#$
54-2×19=16,
16+19×(30-1)=567,
MNOPEFGH(QRSPEFGH(EI(
TUVWX
016
Q
567.
20.
!
:(1)
YZ[\[
1
M]
:
(2)
9^:;
:x=10,
y= 15(40+75+70+90+105)=76,
MN
b^=
∑
5
i=1
xiyi-5xy
∑
5
i=1
x2i-5x
2
=4010-5×10×76
520-5×102
=10.5,
MN
a^=y-b^x=76-10.5×10=-29,
MNM_`abcdeX
y^=10.5x-29.
(3)
#`abcdeX
y^=10.5x-29,
MNf
x=
12
g
,y^=97,
hijPkl$
120m2
(mnop(p
qrX
97
s@
.
21.
!
:(1)
Itu
[60,65)
v(wx
=1-(0.03
+0.07+0.03+0.02+0.01)×5=0.2,
<
wx
yz
=0.25 =0.04,{|(wxV}bd[\
[
2
M]
.
(2)
~����5$
n,
9
200
n =0.2,:;n=1000.
It��
65kg
(��5$
(0.03+0.02+0.01)
×5×1000=300,
u
[65,70)
(�5$
0.03×5×1000=150,
�G
H(�5$
6×150300=3,
u
[70,75)
(�5$
0.02×5×1000=100,
�G
H(�5$
6×100300=2,
u
[75,80]
(�5$
0.01×5×1000=50,
�GH
(�5$
6×50300=1,
MNu
[65,70),[70,75),[75,80]
���GH(
�5VW$
3,2,1.
(3)
��5$
60kg,
�15$
(52.5×0.03+57.5×0.07+62.5×0.04+67.5
×0.03+72.5×0.02+77.5×0.01)×5=61.75(kg).
22.
!
:(1)
ABC
,
;
10×(2a+0.02+0.03+
0.04)=1,
�;
a=0.005.
(2)100
�������(�1V$
55×0.05+65
×0.4+75×0.3+85×0.2+95×0.05=73
V
.
(3)
5���u
[50,60)
(�5$
100×0.05=5,
5���u
[60,70)
(�5$
100×0.4×12 =20,5
���u
[70,80)
(�5$
100×0.3×43 =40,5�
��u
[80,90)
(�5$
100×0.2×54 =25.
MN5���u
[50,90)
J�(�5$
100-5-
20-40-25=10.
"#$%&'
3
()*+,
(
-
)
.
、
/0,
1.C; 2.B; 3.C; 4.B; 5.C; 6.C;
7.D; 8.D; 9.D; 10.B; 11.C; 12.C.
12
:
6.
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3
y
,
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;
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�
;
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,
¢£¤¥(��ªXM°(��
.
#±R²³D�h:°´¤¥(��
.
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(C).
7.
¶·e¸¹[
,
º�»¼.½:¾
,
OP�»¼
:;
t=66,i=1;
O¬�»¼:;
t=56,i=2;
O�
�»¼:;
t=46,i=3,……,
O¿�»¼:;
t=6,
i=7;
OÀ�»¼:;
t=-4,i=8;
9BC:¾
,
±g
Á»¼
,
:¾
-4≤a<6,MNa∈[-4,6).
8.
O
1
Ã
:n=1,k=0,n
©XÄ5
,n=4,k=1;
O
2
Ã
:n=4,k=1,n
XÄ5
,n=2,k=2;
O
3
Ã
:n=2,k=