# 2012 December(71A) Math Question 1

Choice C

$$0.75(120)+20(2)=90+40=130$$

# 2012 December(71A) Math Question 2

Choice G

$$15=3\times5$$ $$6=2\times3$$ $$4=2\times2$$ $$2\times2\times3\times5=60$$

# 2012 December(71A) Math Question 3

Choice D

$$(36+24)2=120$$

# 2012 December(71A) Math Question 4

Choice J

$$180°-64°=116°$$

# 2012 December(71A) Math Question 5

Choice B

$$\frac{1}{4}\times\frac{250}{10}=\frac{1}{4}\times25=6\frac{1}{4}$$

# 2012 December(71A) Math Question 6

Choice F

$$3:12=1:4$$

# 2012 December(71A) Math Question 7

Choice C

$$-(-1)+(-3)+2$$ $$=1-3+2$$ $$=0$$

# 2012 December(71A) Math Question 8

Choice G

$$9+3x=27$$ $$3x=27-9=18$$ $$x=6$$ $$2x=12$$

# 2012 December(71A) Math Question 9

Choice A

$$100(5+0.1-0.08+0.03)$$ $$=100(5+0.05)$$ $$=505$$

# 2012 December(71A) Math Question 10

- Cost

Choice J

$$32000(1+0.035)$$ $$=32000+1120$$ $$=33120$$

# 2012 December(71A) Math Question 11

Choice E

$$\frac{1}{3}(\frac{5}{6}+\frac{1}{12}+\frac{1}{3})$$ $$=\frac{1}{3}(\frac{10}{12}+\frac{1}{12}+\frac{4}{12})$$ $$=\frac{1}{3}(\frac{15}{12})$$ $$=\frac{5}{12}$$

# 2012 December(71A) Math Question 12

Choice H

$$4x-2\geq6$$ $$4x\geq8$$ $$x\geq2$$ $$\Rightarrow H.$$

# 2012 December(71A) Math Question 13

Choice C

$$1500+900=2400$$ $$2400\div20=120$$

# 2012 December(71A) Math Question 14

Choice H

$$\angle A=\angle B=\angle C=60°$$ $$x°=180°-60°=120°$$

# 2012 December(71A) Math Question 15

Choice E

$$16x^{2}=30$$ $$x^{2}=\frac{30}{16}$$ $$x=\sqrt{\frac{30}{16}}$$

# 2012 December(71A) Math Question 16

Choice F

$$100(20)+30(40-20)$$ $$=2000+600$$ $$=2600$$ $$2600\div800=3\frac{1}{4}$$

Choice A

# 2012 December(71A) Math Question 18

Choice G

$$50~100\Rightarrow 89,96$$ $$101~150\Rightarrow 103,104,106,113$$ $$151~200\Rightarrow 160,160,161$$

# 2012 December(71A) Math Question 19

Choice D

$$\frac{89}{x}=\frac{43}{100}$$ $$43x=8900$$ $$x=206.97$$

# 2012 December(71A) Math Question 20

Choice K

$$160+1006+104+113+160+103+161+89+96=1092$$ $$\Rightarrow\frac{1092+x+y}{9+2}=\frac{1092+x+y}{11}$$

# 2012 December(71A) Math Question 21

Choice B

$$\frac{3}{5}=\frac{8+r}{8+5+11+r}=\frac{8+r}{24+r}$$ $$3(24+r)=5(8+r)$$ $$72+3r=40+5r$$ $$32=2r$$ $$r=16$$

# 2012 December(71A) Math Question 22

Choice G

$$(5x^{3}-4x^{2}+7x-3)-(3x^{3}+4x^{2}-3x+1)$$ $$=2x^{3}-8x^{2}+10x-4$$

# 2012 December(71A) Math Question 23

Choice E

$$\Rightarrow (E)$$

# 2012 December(71A) Math Question 24

Choice J

$$f(-4)$$ $$=5(-4)^{2}-2(-4)+10$$ $$=5(16)+8+10$$ $$=80+8+10$$ $$=98$$

# 2012 December(71A) Math Question 25

Choice D

$$\frac{6}{12}=0.5$$ $$\Rightarrow (D)$$

# 2012 December(71A) Math Question 26

Choice H

$$\tan\theta=\frac{3}{8}$$ $$\theta=\arctan\frac{3}{8}$$

# 2012 December(71A) Math Question 27

Choice E

$$2+3d+2=22$$ $$\Rightarrow 4+3d=22$$

# 2012 December(71A) Math Question 28

Choice G

$$3x+5y=6$$ $$5y=-3x+6$$ $$y=-\frac{3}{5}+6$$ $$m=-\frac{3}{5}$$

# 2012 December(71A) Math Question 29

Choice C

$$3x-12-2x+6=-5x-15+6$$ $$x-6=-5x-9$$ $$6x=-3$$ $$x=-\frac{1}{2}$$

Choice H

# 2012 December(71A) Math Question 37

Choice B

$$2w+7=\mid-2\mid$$ $$\mid-2\mid=2$$ $$2w+7=2\Rightarrow w=-2.5$$

# 2012 December(71A) Math Question 38

Choice K

$$\Rightarrow (K)$$

# 2012 December(71A) Math Question 39

Choice B

$$\frac{12+(-4)}{2}=4$$ $$\frac{18+2}{2}=10$$ $$\Rightarrow (4,10)$$

# 2012 December(71A) Math Question 40

Choice G

$$\frac{\sin 58°}{50}=\frac{\sin 68°}{\overline{AB}}$$

# 2012 December(71A) Math Question 41

Choice D

$$\frac{0+8}{2}=4$$ $$\frac{6+0}{2}=3$$

Choice J

# 2012 December(71A) Math Question 43

$$\frac{4x}{6x^{2}}=\frac{2}{3x}$$

A rational number is …

# 2012 December(71A) Math Question 44

Choice K

$$g(-2)=2(-2)-1=-5$$ $$f(-5)=3(-5)+2=-13$$

# 2012 December(71A) Math Question 45

Choice B

$$36=6\times6$$ $$6\times4=24$$

Choice F