Topic Quiz A.3: Linear inequalities

Question 1 of 10 · Solve linear inequalities

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What values of x make x - 9 \ge -14 true? Choose the solution set.

Answer choices
Hint

What is being done to x? Undo it on both sides. Does the negative number on the right affect the direction of the sign?

Question 2 of 10 · Solve linear inequalities

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When x is isolated, what does \dfrac{x}{4} > -2.5 become?

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Hint

x is divided by a positive 4. The number on the right is negative — does that matter?

Question 3 of 10 · Solve linear inequalities

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Which inequality gives every solution of \dfrac{x + 8}{3} \le 5?

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Hint

The whole expression x + 8 is divided by 3. Which operation should you undo first?

Question 4 of 10 · Graph solutions on a number line

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Which situation could be represented by the graph below?

Number line from 0 to 60 labelled every 10, with a closed circle at 30 and shading to the left. 0 10 20 30 40 50 60
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Hint

Write the inequality the graph shows. Then translate each situation into an inequality and compare.

Question 5 of 10 · Graph solutions on a number line

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The solution set of -7 < 2x + 1 \le 9 is graphed on a number line. How many integers are in the solution set?

Type your answer in the box. Fractions like 3/4 are fine.

Hint

Do the same operation to all three parts of the compound inequality. Then decide which endpoints are included before you count.

Question 6 of 10 · Real-world inequalities

A pharmacy cooler must keep a vaccine between 2°C and 8°C, inclusive. When the cooler is switched on, the vaccine is at 14°C, and its temperature drops 1.5°C per minute. For which numbers of minutes t after switching on is the vaccine in the safe range?

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Hint

The temperature after t minutes is 14 - 1.5t. Put it between 2 and 8, and remember what happens when you divide by a negative.

Question 7 of 10 · Write inequalities from context

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A storage unit costs $45 per month plus a one-time $30 move-in fee. Ella can spend at most $300 in total. Complete the inequality for the number of months m she can rent the unit.

m\ + \le 300

Type your answer in the box. Fractions like 3/4 are fine.

Hint

Which number is charged every month? Which is charged only once?

Question 8 of 10 · Graph solutions on a number line

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Jorge graphed the solution set of \dfrac{x}{-2} + 1 \le 3 as shown.

Jorge's graph: number line from -6 to 6 with a closed circle at 4 and shading to the left. −6 −5 −4 −3 −2 −1 0 1 2 3 4 5 6

Select all the errors in Jorge's graph.

Select all that apply.

Answer choices
Hint

Solve the inequality completely. Then compare the boundary, the circle type, and the direction with Jorge's graph one at a time.

Question 9 of 10 · Real-world inequalities

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A rideshare driver earns a daily bonus plus a fixed amount per ride. The table shows her total earnings for some days.

Rides in a day51015
Total earnings$62$112$162

She wants to earn at least $400 in one day. What is the least number of rides she must give?

rides

Type your answer in the box. Fractions like 3/4 are fine.

Hint

How much do 5 more rides add? Use that to find the earnings per ride, then the bonus.

Question 10 of 10 · Write inequalities from context

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Maria works two part-time jobs. She earns $16 per hour at a store and $22 per hour tutoring. She must earn at least $600 per week, and she can work at most 35 hours per week in total. Let s be her store hours and t her tutoring hours. Which system of inequalities represents this situation?

Answer choices
Hint

Write one inequality for money and one for time. Which numbers go with money, and which with hours?

Formula sheet

Area

Area of a square s = length of a side
A = s^2
Area of a rectangle l = length, w = width
A = lw
Area of a parallelogram b = base, h = height (straight up from the base, not the slanted side)
A = bh
Area of a triangle b = base, h = height
A = \tfrac{1}{2}bh
Area of a trapezoid b_1 and b_2 = the two parallel sides, h = height
A = \tfrac{1}{2}h(b_1 + b_2)
Area of a circle r = radius (half of the diameter); \pi \approx 3.14
A = \pi r^2

Perimeter and circumference

Perimeter of a square s = length of a side
P = 4s
Perimeter of a rectangle l = length, w = width
P = 2l + 2w
Perimeter of a triangle s_1, s_2, s_3 = the three side lengths
P = s_1 + s_2 + s_3
Circumference of a circle the distance around a circle; r = radius, d = diameter, \pi \approx 3.14
C = 2\pi r = \pi d

Surface area (SA) and volume (V)

p = perimeter of the base with area B; \pi \approx 3.14

Rectangular prism l = length, w = width, h = height
SA = 2lw + 2lh + 2wh \qquad V = lwh
Right prism B = area of the base, p = perimeter of the base, h = height
SA = ph + 2B \qquad V = Bh
Cylinder r = radius of the base, h = height
SA = 2\pi rh + 2\pi r^2 \qquad V = \pi r^2 h
Pyramid B = area of the base, p = perimeter of the base, s = slant height, h = height
SA = \tfrac{1}{2}ps + B \qquad V = \tfrac{1}{3}Bh
Cone r = radius of the base, s = slant height, h = height
SA = \pi rs + \pi r^2 \qquad V = \tfrac{1}{3}\pi r^2 h
Sphere r = radius
SA = 4\pi r^2 \qquad V = \tfrac{4}{3}\pi r^3

Data

Mean (average) add all the values of the data set, then divide by how many values there are
\text{mean} = \dfrac{\text{total of the values}}{\text{number of values}}
Median
the middle value when the data are in order; with an even number of values, it is the mean of the two middle values

Algebra

Slope of a line (x_1, y_1) and (x_2, y_2) = two points on the line
m = \dfrac{y_2 - y_1}{x_2 - x_1}
Slope-intercept form of a line m = slope, b = y-intercept (where the line crosses the y-axis)
y = mx + b
Point-slope form of a line m = slope, (x_1, y_1) = a point on the line
y - y_1 = m(x - x_1)
Standard form of a quadratic equation a, b, c are numbers and a \ne 0
y = ax^2 + bx + c
Quadratic formula solves ax^2 + bx + c = 0
x = \dfrac{-b \pm \sqrt{b^2 - 4ac}}{2a}
Pythagorean theorem in a right triangle: a, b = the two legs, c = the hypotenuse (the longest side, across from the right angle)
a^2 + b^2 = c^2
Simple interest I = interest, P = principal (the amount saved or borrowed), r = rate per year as a decimal, t = time in years
I = Prt
Distance = rate × time d = distance, r = rate (speed), t = time
d = rt
Total cost
\text{total cost} = (\text{number of units}) \times (\text{price per unit})