ACT Form 67F Math Answer Explanation



Choice D

$$6\times$10=$60$$ $$$60\div(6-1)=$12$$


2011 April(67F) Math Question 2

Word Problems

- Cost


Choice G

$$$58.95\times0.8=$47.16$$


Choice C

$$30:44=70:x$$ $$44\times70=30x$$ $$x=102.66$$


Choice F

$$(5+2-(-3)(2+(-3))$$ $$=(5+2+3)(2-3)$$ $$=(10)(-1)$$ $$=-10$$


Choice A

To maximize the value of x, you must minimize the value of

$$y^{2}$$ $$y^{2}=0,\ x^{2}=256$$ $$x=\pm\sqrt{256}=\pm16$$

The positive 16 is the answer.


2011 April(67F) Math Question 6

Sequences and Patterns

- Logical Expressions


Choice J

If Antoine rode the roller coaster, he must be more than 4 feet tall.


Choice C

$$N(4)=\frac{1200\times4^{2}+10}{4^{2}+1}$$ $$=\frac{1200\times16+10}{16+1}$$ $$=\frac{19200}{17}$$ $$\approx 1130$$


Choice J

$$3x^{5}\cdot7x^{9}=(3\cdot7)(x^{5}\cdot x^{9})$$ $$=21x^{14}$$


2011 April(67F) Math Question 9

Probability

- One Event


Choice B

$$\frac{3}{5+4+3}=\frac{3}{12}=\frac{1}{4}$$


Choice G

$$35=5\times7$$ $$56=2^{3}\times7$$ $$16=2^{4}$$ $$\Rightarrow2^{4}\times5\times7=16\times5\times7=560$$


2011 April(67F) Math Question 11

Angles

- Collinear Points & Triangles


Choice B

Because triangles ABC and DEC are congruent,

$$\angle CAB=\angle CDE$$ $$\angle CDE= 180° – 45° – 70° = 65°$$


Choice F

$$=\frac{\frac{57}{7}}{\frac{15}{14}}$$ $$=\frac{57}{7}\times\frac{14}{15}$$ $$=\frac{114}{15}$$ $$=\frac{38}{5}$$


Choice D

$$x + y = 15 ---(1)$$ $$x – y = 9---(2)$$ $$(1)+(2)$$ $$2x=24$$ $$x=12$$ $$y=3$$ $$xy=12(3)=36$$


2011 April(67F) Math Question 14

Sequences and Patterns

- General Sequences


Choice J

1. Draw A as a point on a circle.

2. Draw B 6 units counterclockwise from A.

3. Draw C 2 units clockwise from point A, between A and B in the clockwise direction.

4. Draw D 9 units clockwise from A, between C and B in the clockwise direction.

Now your points are in the correct order, A, C, B, D in the clockwise direction.


2011 April(67F) Math Question 15

Statistics

- Mean, Median


Choice D

$$\frac{(83 + 88 + 92 + 99)}{4}=90.5$$


Choice K

$$ Slope-intercept (y = mx + b) form$$ $$ 6x – 2 = y \Rightarrow y = 6x – 2$$


2011 April(67F) Math Question 17

Quadratic Equations

- Factoring


Choice B

$$ \Rightarrow (x – 7)(x + 4) = 0$$ $$ x=7,-4$$ $$ 7+(-4)=3$$


2011 April(67F) Math Question 18

Absolute Values

- Absolute Value Expressions


Choice G

$$=\mid-20+18\mid=\mid-2\mid=2$$


2011 April(67F) Math Question 19

Number Types & Properties

- Order of Values


Choice C

$$\frac{3}{8}=0.375$$ $$\frac{5}{16}=0.3125$$ $$\frac{11}{32}=0.34375$$


Choice K

$$Slope=\frac{(y2 – y1)}{(x2 – x1)}$$ $$=\frac{10-8}{-2-3}$$ $$=\frac{2}{-5}$$


Choice E

$$a + a + b …


2011 April(67F) Math Question 22

Graphing Properties

- Interpret Graphs or Figures


Choice H

$$\frac{250}{875}$$ $$=0.286 $$


2011 April(67F) Math Question 23

Sequences and Patterns

- Arithmetic Sequences


Choice B

$$37-13=24$$ $$24=3\times8$$ $$13,16,19,22,25,28,31,34,37$$

The question …


2011 April(67F) Math Question 24

Quadratic Equations

- FOIL


Choice F

$$x^{2}\neq49\Rightarrow x\neq\pm7$$ $$x^{2}-49=(x+7)(x-7)$$ $$\Rightarrow\frac{(x-7)(x-7)}{(x+7)(x-7)}$$ $$=\frac{(x-7)}{(x+7)}$$


2011 April(67F) Math Question 25

Perimeter, Area, Volume

- Mixed Shapes


Choice C

$$12:8=15:x$$ $$8\times15=12x$$ $$x=10$$


Choice H

When x -2, (x + …


2011 April(67F) Math Question 27

Perimeter, Area, Volume

- Other Shapes


Choice B

$$z + 2(z + 2) …


2011 April(67F) Math Question 28

Equation of a Line

- Distance & Midpoint


Choice G

67f

B is 10 blocks east …


Choice E

$$b=6c \Rightarrow c=\frac{1}{6}b$$ $$a=2c=2(\frac{1}{6}b)=\frac{1}{3}b$$


2011 April(67F) Math Question 30

Word Problems

- Temperature


Choice J

$$\frac{5}{9}(59-32)=\frac{5}{9}\times27=15$$ $$\frac{5}{9}(68-32)=\frac{5}{9}\times36=20$$ $$\Rightarrow 15° \leq …


2011 April(67F) Math Question 31

Angles

- Other Shapes


Choice C

By parallel line properties,

$$\angle …


Choice J

67f

$$6\times6\times5=180$$


2011 April(67F) Math Question 33

Perimeter, Area, Volume

- Other Shapes


Choice E

67f

The triangle is a 3-4-5 …


Choice H

67f

Shade any square whose reflection …


Choice C

$$4x(x)=80$$ $$\Rightarrow 4x^{2}=80$$ $$\Rightarrow x=\sqrt{20}$$ …


2011 April(67F) Math Question 36

Perimeter, Area, Volume

- Other Shapes


Choice K

The volume of this rectangular …


2011 April(67F) Math Question 37

Statistics

- Mean, Median, Mode Combinations


Choice B

$$t = 10f – 20$$ …


2011 April(67F) Math Question 38

Trigonometry

- Pythagorean Theorem & sin cos tan


Choice G

$$Tangent=\frac{opposite}{adjacent}$$ $$\tan25°=\frac{x}{100}$$ $$x=100\tan25°=100\times0.47=47$$


2011 April(67F) Math Question 39

Trigonometry

- Pythagorean Theorem & sin cos tan


Choice E

67f

3-4-5 triangle (6-8-10)


2011 April(67F) Math Question 40

Perimeter, Area, Volume

- Mixed Shapes


Choice J

$$4^{3}=64$$ $$4\times3=12$$ $$12^{3}=1728$$

The volume …


2011 April(67F) Math Question 41

Conics

- Circles


Choice E

$$(x-h)^{2}+(y-k)^{2}=r^{2}$$

Based on this equation, …


Choice J

The perimeter of a rectangle …


2011 April(67F) Math Question 43

Perimeter, Area, Volume

- Mixed Shapes


Choice A

There are 2 possible vertical …


Choice F

The current area of the …


2011 April(67F) Math Question 45

Trigonometry

- Graphing Trig Functions


Choice E

Compared to y = cos …


2011 April(67F) Math Question 46

Number Types & Properties

- Order of Values


Choice K

$$0\lt p\lt q$$

(F)\ 0\lt …


Choice D

$$a=b\times0.25$$ $$\frac{b\times1.35}{b\times0.25}=\frac{1.35}{0.25}=5.4$$


2011 April(67F) Math Question 48

Trigonometry

- Advanced sin, cos, tan functions


Choice H

67f

$$\sin^{2}\theta+\cos^{2}\theta-4$$ $$=1-4$$ $$=-3$$


Choice E

67f

Therefore, the line of reflection …


2011 April(67F) Math Question 50

Angles

- Circles


Choice H

$$\frac{x}{144°}=\frac{60}{360°}$$ $$x=144\times\frac{60}{360}=24$$


2011 April(67F) Math Question 51

Graphing Properties

- Create Graphs or Figures


Choice B

The plane section of such …


2011 April(67F) Math Question 52

Logarithms

- Logarithm Expressions


Choice F

$$\log x=y \Rightarrow a^{y}=x$$ $$b^{4}=81$$ …


Choice D

f(x + a) + b …


2011 April(67F) Math Question 54

Angles

- Parallel Lines


Choice F

Based on parallel line properties, …


Choice D

To maximize the value of P(x,y), you must maximize the value of 4x + 3y.

At point B, P(x,y) = 4 • 0 + 3 • 4 = 12.

At point C, P(x,y) =4 • 4 + 3 • 0 = 16.

The value of P(x,y) is higher at point C then at point B and points B and C are connected by a straight line delineating an edge of the shaded region, no other points along this line or anywhere else in the shaded region can have a higher value than point C.


Choice F

(F) Look at the graph of P(x,y) above question 55 and compare it to the graph in 56 that labels the quadrants. P(x,y) contains points in quadrants I and II only.


2011 April(67F) Math Question 57

Trigonometry

- Pythagorean Theorem & sin cos tan


Choice A

67f

Tangent is defined as opposite/adjacent. …


Choice K

If f(x)=0 when x=3, (x …


Choice C

$$\frac{5}{1000000}=5\cdot 10^{-6}$$


2011 April(67F) Math Question 60

Quadratic Equations

- FOIL


Choice F

$$(a^{2}-b^{2})=(a+b)(a-b)$$ $$(a – b)\gt (a …