Cambridge International Mathematics

ANSWERS 721

c

6a iopens upwards ii 12 iii 2 (touching) iv x=2

b

7a i¡ 10 ii 2 and 5 iii x=^72 iv (^72 ,^94 )

b

8ah=2 ba=¡^34 , k=3^12

9a b

10 f(x)=x^2 +2x¡ 15 11 f(x)=¡(x¡2)^2 +2

12 f(x)=¡ 2 x^2 ¡ 16 x¡ 17 13 45 or¡ 1

14

p

3 ¡^32 and

p

3+^321512 grandchildren

16 CX=60m, AY¼ 34 : 377 m

CHALLENGE

1b 318 when x=^142150 of them

344 : 4 mby 50 m for each

EXERCISE 22A

1a inegative association ii linear iiistrong

bino association

cipositive association ii linear iiimoderate

dipositive association ii linear iiiweak

eipositive association ii not linear iiimoderate

finegative association ii not linear iiistrong

2a“...... asxincreases,yincreases”

b“...... asTincreases,ddecreases”

c“...... randomly scattered”

3a i

ii A moderate, positive, linear association.

b

A weak, negative, linear association (virtually zero

association).

4

A moderate, positive, linear association exists between

TemperatureandSales.

5

A weak, positive, linear association exists betweenShoe sizeand

Height.

EXERCISE 22B

1aMinutes spent preparing(x) bx¼ 61 : 5 , y¼ 35 : 7

c

dThere is a weak, positive correlation between the variables.

x

y

@\=\!X

@\=\-(!-1)X-3

-4O(1' -3)

x

y

@\=\3(!-2)X

12

(2' 0)

!=2

O

x

y

@\=\-!X+7!-10

25

(Uw_\'Or_)

x¡= ¡\Uw_

O

80

70

60

50

40

40 50 60 70 80 90

Ma

Pc

90

80

70

60

Art

Pc

40 50 60 70 80 90

25

20

15

10

5

5 10 15 20 25

Sales ( '000)£

Temp (°C)

0

0

7

6

5

4

140 145 150 155 160 165

Shoe size

Height

60

50

40

30

20

10

(^050100150200)
Test score,y
Time (min),x
0
()xy,¡
-1 3
-6
x
y
O
¦()xx x¡=¡2 ¡-3( )(¡+¡1)
-4
y
O x
gx()¡=¡-xx(¡+¡4)
IB MYP_3 ANS
cyan magenta yellow black
(^05255075950525507595)
100 100
(^05255075950525507595)
100 100
Y:\HAESE\IGCSE01\IG01_an\721IB_IGC1_an.CDR Thursday, 20 November 2008 4:48:07 PM PETER