# 2016 April(72E) Math Question 1

Choice D

$$\frac{x}{72}=\frac{1\frac{3}{4}}{24} \\$$ $$\Rightarrow x=5\frac{1}{4}$$

# 2015 December(72E) Math Question 2

Choice H

$$\frac{57+61+57+57+58+57}{6}=57.8$$

# 2015 December(72E) Math Question 3

Choice A

$$120=1.8K-459.67 \\$$ $$\Rightarrow K\approx 322$$

# 2015 December(72E) Math Question 4

Choice F

$$-\frac{18}{3}x^{3-1}y^{2-1}=-6x^2y$$

# 2015 December(72E) Math Question 5

Choice C

$$\sqrt{a}=9 \Rightarrow a=81$$

# 2015 December(72E) Math Question 6

- Cost

Choice G

$$\frac{80\times15\%}{5}=2.4$$

# 2015 December(72E) Math Question 7

Choice B

$$0.000000000087=8.73\times 10^{-11}$$

# 2015 December(72E) Math Question 8

Choice J

$$\frac{360}{6}=60$$

# 2015 December(72E) Math Question 9

Choice E

$$\frac{4+45}{9}=\frac{49}{9}$$

# 2015 December(72E) Math Question 10

Choice G

$$\begin{bmatrix}2\times1+3\times2 & 2\times2+3\times1 \\2\times3-3\times1 & 2\times4-3\times2 \end{bmatrix}=\begin{bmatrix}8 & 7 \\3 & 2 \end{bmatrix}$$

# 2015 December(72E) Math Question 11

Choice D

The speed of one motorcycle exceeds 4 times the speed of another motor cycle by 24 mph: 4g+24

# 2015 December(72E) Math Question 12

Choice J

$$Area=\frac{12\times8}{2}=48$$

# 2015 December(72E) Math Question 13

Choice C

Only the equation in C fulfils all data sets in the table.

# 2015 December(72E) Math Question 14

Choice H

$$Driving \ time = \frac{1200}{50}=24 \\$$ $$Unloading \ time = 12 \\$$ $$\Rightarrow Total \ time=24+12+30=66=24+24+18$$

# 2015 December(72E) Math Question 15

Choice C

$$x+5y=3 \Rightarrow x=-5y+3$$

# 2015 December(72E) Math Question 16

Choice H

Thus the other side is also 16; the remaining 2 sides are: $$\frac{80-16-16}{2}=24$$

# 2015 December(72E) Math Question 17

Choice D

$$6l+4s=26 \\$$ $$2l+4x=14 \\$$ $$\Rightarrow l=3$$

# 2015 December(72E) Math Question 18

Choice K

$$2\times6\times5=60$$

# 2015 December(72E) Math Question 19

Choice C

$$26+2\times5+1.5\times \frac{12}{3}=42$$

Choice K

180-34=146

# 2015 December(72E) Math Question 21

Choice E

$$200x=500+20\times30 \\$$ $$\Rightarrow x=5.5$$

# 2015 December(72E) Math Question 22

Choice K

$$\frac{9}{10+5+10+9+9+7}=18\%$$

# 2015 December(72E) Math Question 23

Choice B

The length of the rectangle is w + 12; the area is $$w\cdot l=140 \\$$ $$\Rightarrow w\cdot (w+12)=140$$

# 2015 December(72E) Math Question 24

Choice H

$$\sqrt{(-8-4)^2+(4-9)^2}=\sqrt{169}$$

# 2015 December(72E) Math Question 25

Choice E

(6,3+(7-3)+(7-3))=(6,11)

Choice H

Choice B

g(1) > 0

g(2) > 0

g(3) …

# 2015 December(72E) Math Question 34

Choice J

$$b=3n \\$$ $$\Rightarrow \frac{1}{b}+\frac{1}{n}=\frac{1}{3n}+\frac{1}{n}=\frac{...}{3n}$$

# 2015 December(72E) Math Question 35

Choice E

$$g=b+15 \\$$ $$r=g+24=b+39 \\$$ …

# 2015 December(72E) Math Question 36

Choice K

$$(5-2)\times 180°-70°-100°-110°-135°=125°$$

# 2015 December(72E) Math Question 37

Choice A

$$WD=\frac{6}{2}=3 \\$$ $$WA=\frac{8}{2}=4 \\$$ …

Choice G

OS=2r

Thus S(0, -2r)

# 2015 December(72E) Math Question 39

Choice B

‘x varies directly with y’ …

Choice G

Choice K

K: |x|=x

When x is …

# 2015 December(72E) Math Question 49

Choice A

$$Area = \frac{AB+CD}{2}\cdot EF=\frac{8+12}{2}\cdot 6=60$$

# 2015 December(72E) Math Question 50

Choice J

$$x^2={\sqrt{a}}^2=a$$

# 2015 December(72E) Math Question 51

Choice A

$$\tan\alpha=\frac{50-5}{80}=\frac{45}{80}$$

# 2015 December(72E) Math Question 52

Choice G

Firstly, one need to identify …

# 2015 December(72E) Math Question 53

Choice A

$$\frac{3}{6}\cdot\frac{1}{6}=\frac{1}{12}$$

# 2015 December(72E) Math Question 54

Choice H

$$Area = (18-2x)(12-x)=2x^2-42x_216$$

# 2015 December(72E) Math Question 55

Choice B

The graph is reflected over …

# 2015 December(72E) Math Question 56

Choice K

$$\frac{x^{24}}{x^6}\cdot x^2=x^{24+2-6}=x^{20}$$

Choice A