Free Full Length STAAR Grade 8 Practice Test

The correct answer is $$23.8$
Let $x$ be the number of cans.
Write the proportion and solve for $x$.
$\frac{5 \ cans}{$ 3.40}= \frac{35 \ cans}{x}$
$x =\frac{3.40 \ × \ 35}{5} ⇒x=$23.8$

The correct answer is $x \ < \ 3$
$2 \ x \ + \ 4 \ > \ 11 \ x \ - \ 12.5 \ - \ 3.5 \ x→$
Combine like terms:
$2 \ x \ + \ 4 \ > \ 7.5 \ x \ - \ 12.5→$ Subtract $2 \ x$ from both sides: $4 \ > \ 5.5 \ x \ - \ 12.5$
Add $12.5$ both sides of the inequality.
$16.5 \ > \ 5.5 \ x$, Divide both sides by $5.5$.
$\frac{16.5}{5.5} \ > \ x→$
$x \ < \ 3$

The correct answer is $97.6$
Area of a square: S $= a^2 ⇒ 595.36 = a^2 ⇒ a = 24.4$
Perimeter of a square: P $= 4 \ a ⇒$ P $= 4 \ × \ 24.4 ⇒$ P $= 97.6$

The correct answer is $2.25$ ft.
Write the proportion and solve for the missing number.
$\frac{32}{12} = \frac{6}{x}→$
$32 \ x=6 \ × \ 12=72$
$32 \ x=72→$
$x=\frac{72}{32}=2.25$

The correct answer is $400$
Let $x$ be the original price.
If the price of a laptop is decreased by $10\%$ to $$360$, then:
$90\%$ of $x=360⇒$
$0.90\ x=360 ⇒$
$x=360 \ ÷ \ 0.90=400$

The correct answer is $130$
The perimeter of the trapezoid is $54$ cm.
Therefore, the missing side (high) is $= 54 \ – \ 18 \ – \ 12 \ – \ 14 = 10$
Area of a trapezoid: A $= \frac{1}{2} \ h \ (b1 \ + \ b2) = \frac{1}{2} \ (10) \ (12 \ + \ 14) = 130$

A graph represents y as a function of $x$ if
$x_{1}=x_{2}→y_{1}=y_{2}$
In choice C, for each $x$, we have two different values for $y$.

The correct answer is $- \ 8 \ < \ x \ < \ - \ 5$
$13 \ < \ - \ 3 \ x \ - \ 2 \ < \ 22→$
Add $2$ to all sides.
$13 \ + \ 2 \ < \ - \ 3 \ x \ - \ 2 \ + \ 2 \ < \ 22 \ + \ 2→$
$15 \ < \ - \ 3 \ x \ < \ 24→$ Divide all sides by $- \ 3$.
(Remember that when you divide all sides of an inequality by a negative number, the inequality sing will be swapped. $<$ becomes $>$)
$\frac{15}{- \ 3} \ > \ \frac{- \ 3 \ x}{- \ 3} \ > \ \frac{24}{- \ 3}$
$- \ 8 \ < \ x \ < \ - \ 5$

The correct answer is $\frac{1}{6}$
Number of biology book: $35$
Total number of books; $35 \ + \ 95 \ + \ 80=210$
The ratio of the number of biology books to the total number of books is: $\frac{35}{210}=\frac{1}{6}$

The correct answer is $$840$
Use simple interest formula:
$I=prt$
($I =$ interest, $p =$ principal, $r =$ rate, $t =$ time)
$I=(12000) \ (0.035) \ (2)=840$

The correct answer is $16 \ π$
Use the formula for area of circles.
Area $= π \ r^2 ⇒$
$64 \ π = π \ r^2 ⇒$
$64 = r^2 ⇒ r = 8$
Radius of the circle is $8$.
Now, use the circumference formula:
Circumference $= 2 \ π \ r = 2 \ π \ (8) = 16 \ π$

The correct answer is $(200) \ (0.85) \ (0.85)$
To find the discount, multiply the number by ($100\% \ –$ rate of discount).
Therefore, for the first discount we get: $(200) \ (100\% \ – \ 15\%) = (200) \ (0.85)$
For the next $15\%$ discount: $(200) \ (0.85) \ (0.85)$

The correct answer is Mathematics
Compare each mark:
In Algebra Joe scored $20$ out of $25$ in Algebra.
It means Joe scored $80\%$ of the total mark.
$\frac{20}{25} = \frac{x}{100} ⇒x= 80\%$
Joe scored $30$ out of $40$ in science.
It means Joe scored $75\%$ of the total mark.
$\frac{30}{40} = \frac{x}{100} ⇒x= 75\%$
Joe scored $68$ out of $80$ in mathematic that it means $85\%$ of total mark.
$\frac{68}{80} = \frac{x}{100} ⇒x= 85\%$
Therefore, his score in mathematic is higher than his other scores.

The correct answer is $12$ m$^3$
Use the volume of the triangular prism formula.
$V = \frac{1}{2}$ (length) (base) (high)
$V = \frac{1}{2} \ ×\ 4 \ × \ 3 \ × \ 2 ⇒ V = 12$ m$^3$

The correct answer is $0.88$ D
To find the discount, multiply the price by ($100\% \ –$ rate of discount).
Therefore, for the first discount we get: (D) $(100\% \ –\ 20\%) =$ (D) $(0.80) = 0.80$ D
To increase the $10\%:\ (0.80$ D) $(100\% \ + \ 10\%) = (0.85$ D) $(1.10) = 0.88$ D $= 88\%$ of D

The correct answer is $(7, \ - \ 9)$
When a point is reflected over $x$ axes, the $(y)$ coordinate of that point changes to $(- \ y)$ while its $x$ coordinate remains the same.
C $(7, \ 9) →$ C’ $(7, \ - \ 9)$

The correct answer is $0.97$
Ratio of women to men in city A: $\frac{570}{600}=0.95$
Ratio of women to men in city B: $\frac{291}{300}=0.97$
Ratio of women to men in city C: $\frac{665}{700}=0.95$
Ratio of women to men in city D: $\frac{528}{550}=0.96$

The correct answer is $1.05$
Percentage of men in city A $= \frac{600}{1170} \ × \ 100=51.28\%$
Percentage of women in city C $= \frac{665}{1365} \ × \ 100=48.72\%$
Percentage of men in city A to percentage of women in city C $= \frac{ 51.28}{48.72}=1.05$

The correct answer is $12$
let $x$ be the number of gallons of water the container holds when it is full.
Then; $\frac{7}{24} \ x=3.5→$
$x=\frac{24 \ × \ 3.5}{7}=12$

The correct answer is $4$
$(3^a )^b=81→3^{a \ b}=81$
$81=3^4→3^{a \ b}=3^4$
$→a \ b=4$

The correct answer is $− \ 8 \ < \ x \ < \ − \ 5$
$13 \ < \ - \ 3 \ x \ - \ 2 \ < \ 22→$ Add $2$ to all sides.
$13 \ + \ 2 \ < \ - \ 3 \ x \ - \ 2 \ + \ 2 \ < \ 22 \ + \ 2$
$→15 \ < \ - \ 3 \ x \ < \ 24→$ Divide all sides by $- \ 3$.
(Remember that when you divide all sides of an inequality by a negative number, the inequality sing will be swapped. $<$ becomes $>$)
$\frac{15}{- \ 3} \ > \ \frac{- \ 3 \ x}{- \ 3} \ > \ \frac{24}{- \ 3}$
$- \ 8 \ < \ x \ < \ - \ 5$

The correct answer is $\frac{5}{2}$
The value of y in the x-intercept of a line is zero. Then:
$y=0→2 \ x \ - \ 2 \ (0)=5 → 2 \ x=5→x=\frac{5}{2}$
then, $x-$intercept of the line is $\frac{5}{2}$

The correct answer is $x \ ≤ \ – \ 3$
Simplify:
$10 \ – \ \frac{2}{3} \ x \ ≥ \ 12 ⇒$
$– \ \frac{2}{3} \ x \ ≥ \ 2 ⇒$
$– \ x \ ≥ \ 3 ⇒$
$x \ ≤ \ – \ 3$

The correct answer is $84$
$120 \ × \ \frac{70}{100 }= 84$

The correct answer is $y = x \ + \ 1$
Solve for each equation:
$(− \ 1, 2)$
A. $y = 1 \ – \ x ⇒ 2 = 1 \ – \ (– \ 1) ⇒ 2 = 2$
B. $y = x \ + \ 1 ⇒ 2 = \ – \ 1 \ + \ 1 ⇒ 2 ≠ 0$
C. $x = \ – \ 1 ⇒ \ – \ 1 = \ – \ 1$
D. $y = x \ + \ 3 ⇒ 2 = \ – \ 1 \ + \ 3 ⇒ 2 = 2$

The correct answer is $(3, 18)$
$y = 5 \ x \ – \ 3$
A. $(1, 2)$            $⇒ 2 = 5 \ – \ 3 ⇒ 2 = 2$
B. $(–\ 2, – \ 13)$   $⇒ \ – \ 13 = \ – \ 10 \ – \ 3 ⇒ \ – \ 13 = \ – \ 13$
C. $(3, 18)$          $⇒ 18 = 15 \ – \ 3 ⇒ 18 ≠ 12$
D. $(2, 7)$            $⇒ 7 = 10 \ – \ 3 ⇒7 = 7$

The correct answer is $35$
$a \ + \ b \ + \ c = 45$
$\frac{a \ + \ b \ + \ c \ + \ d}{4 }= 20 ⇒$
$a \ + \ b \ + \ c \ + \ d = 80 ⇒$
$45 \ + \ d = 80$
$d = 80 \ – \ 45 = 35$

The correct answer is $$2660$
$45 \ × \ $124=$5580$ Payable amount is:
$$8240 \ - \ $5580=$2660$

The correct answer is $y = \frac{6}{7} \ x \ + \ \frac{12}{7}$
$- \ 7 \ y= \ - \ 6 \ x \ - \ 12⇒$
$y=\frac{- \ 6}{- \ 7} \ x \ - \ \frac{12}{- \ 7}⇒$
$y=\frac{6}{7} \ x \ + \ \frac{12}{7}$

The correct answer is $(1, 4)$
$\begin{cases}5 \ x \ + \ y=9 \\10 \ x \ - \ 7 \ y = \ - \ 18\end{cases} ⇒$ Multiply $(– \ 2)$ to the first equation $\begin{cases}- \ 10 \ x \ - \ 2 \ y= \ - \ 18 \\10 \ x \ - \ 7 \ y = \ - \ 18\end{cases} ⇒$
Add two equations together $⇒ \  – \ 9 \ y = \ – \ 36 ⇒ y = 4$, then: $x = 1$

The correct answer is $2 \ x \ – \ y = 4$
If two lines are parallel with each other, then the slope of the two lines is the same.
Then in line $y=2 \ x$, the slope is equal to $2$
And in the line $2 \ x \ - \ y=4⇒y=2 \ x \ - \ 4$, the slope equal to $2$

The correct answer is $11$
$\frac{a \ + \ b}{2} = 8 ⇒ a \ + \ b = 16$
$\frac{a \ + \ b \ + \ c}{3} = 9 ⇒ a \ + \ b \ + \ c = 27$
$16 \ + \ c = 27 ⇒ c = 27 \ – \ 16 = 11$

The correct answer is $4 \ x \ – \ 2 \ y = 2 \ x$
$4 \ x \ – \ 2 \ y = 2 \ x$ has a graph that is a straight line.
All other options are not equations of straight lines.

The correct answer is $5$
Use distance formula:
C $= \sqrt{(x_{A} \ - \ x_{B})^2 \ + \ (y \ - \ y_{B})^2 }$
C $= \sqrt{(1 \ - \ (- \ 2))^2 \ + \ (3 \ - \ 7)^2 }$
C $= \sqrt{(3)^2 \ + \ (- \ 4)^2 }$
C $= \sqrt{9 \ + \ 16}$
C $= \sqrt{25} = 5$

The correct answer is $30$ degrees
The sum of supplement angles is $180$.
Let $x$ be that angle. Therefore,
$x \ + \ 5 \ x = 180$
$6 \ x = 180$, divide both sides by $6: \ x = 30$

The correct answer is $30$
Let $x$ be the number.
Write the equation and solve for $x$.
$\frac{2}{3} \ × \ 18= \frac{2}{5 }, x ⇒ \frac{2 \ × \ 18}{3}= \frac{2 \ x}{5}$, use cross multiplication to solve for $x$.
$5 \ × \ 36=2 \ x \ × \ 3 ⇒180=6 \ x ⇒ x=30$

The correct answer is $15$
If the score of Mia was $60$, therefore the score of Ava is $30$.
Since, the score of Emma was half as that of Ava, therefore, the score of Emma is $15$.

The correct answer is $36$
Let $x$ be the smallest number.
Then, these are the numbers:
$x, x \ + \ 1, x \ + \ 2, x \ + \ 3, x \ + \ 4$
average $= \frac{sum \ of \ terms}{number \ of \ terms} ⇒$
$38 = \frac{x \ + \ (x \ + \ 1) \ + \ (x \ + \ 2) \ + \ (x \ + \ 3) \ + \ (x \ + \ 4)}{5}⇒$
$38=\frac{5 \ x \ + \ 10 }{5} ⇒ 190 = 5 \ x \ + \ 10 ⇒$
$180 = 5 \ x ⇒ x=36$

The correct answer is $61.28$
average $= \frac{sum \ of \ terms}{number \ of \ terms}$
The sum of the weight of all girls is: $18 \ × \ 60 = 1080$ kg
The sum of the weight of all boys is: $32 \ × \ 62 = 1984$ kg
The sum of the weight of all students is: $1080 \ + \ 1984 = 3064$ kg
average $= \frac{3064}{50} = 61.28$

The correct answer is $$400$
Let $x$ be the original price.
If the price of a laptop is decreased by $10\%$ to $$360$, then:
$90\%$ of $x=360⇒ 0.90 \ x=360 ⇒ x=360 \ ÷ \ 0.90=400$