Write and Represent Simple Inequalities
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6th Grade Math › Write and Represent Simple Inequalities
An elevator has a weight limit. The sign reads "Maximum capacity: 2000 pounds." If the elevator currently has 1650 pounds of weight, how much additional weight $$w$$ can be added?
$$w \geq 350$$ because at least 350 pounds of space remains available
$$w < 350$$ because the additional weight must be strictly less than 350 pounds
$$w > 350$$ because more than 350 pounds can safely be added
$$w \leq 350$$ because the total weight cannot exceed the maximum capacity
Explanation
Current weight is 1650 pounds, maximum is 2000 pounds, so additional weight plus current weight cannot exceed 2000: $1650 + w ≤ 2000$, which gives $w ≤ 350$. Choice A uses strict inequality, but exactly 350 pounds additional would reach exactly the maximum (allowed). Choices C and D suggest more than 350 pounds can be added, which would exceed the limit.
A school requires students to read at least 20 minutes per day. Jenny reads for $$r$$ minutes on Monday. If she also reads for 15 minutes on Tuesday, which inequality ensures she meets the minimum requirement for both days combined?
$$r \geq 20$$ because each day has an independent 20-minute requirement
$$r + 15 \geq 35$$ because the total must be at least 40 minutes
$$r + 15 > 40$$ because she must exceed the two-day minimum
$$r + 15 \geq 40$$ because she must meet or exceed the minimum
Explanation
The requirement is at least 20 minutes per day, so for 2 days she needs at least 40 minutes total. Jenny reads $r$ minutes Monday plus 15 minutes Tuesday, so $r + 15 ≥ 40$. Choice A uses strict inequality when 'at least' means ≥. Choice C ignores that this is about the combined total. Choice D states the correct reasoning but shows ≥ 35 instead of ≥ 40.
A parking meter accepts coins only if the total value is greater than $0.75. Sarah has quarters ($0.25 each) and wants to determine how many quarters $$q$$ she needs. Which inequality and solution representation is correct?
$$q > 0.75$$; Sarah needs more than 0.75 quarters to operate the meter
$$0.25q < 0.75$$; Sarah needs fewer than 3 quarters to operate the meter
$$0.25q \geq 0.75$$; Sarah needs at least 3 quarters to operate the meter
$$0.25q > 0.75$$; Sarah needs more than 3 quarters, so at least 4 quarters
Explanation
The meter requires a value greater than $0.75, so $0.25q > 0.75$. Solving: $q > 3$. Since Sarah can't use a fraction of a quarter, she needs at least 4 quarters. Choice B uses ≥ and incorrectly concludes 3 quarters is enough. Choice C uses the wrong inequality direction. Choice D omits the 0.25 coefficient and gives a nonsensical interpretation.
A library lets you check out a maximum of 6 books at a time. Let $b$ be the number of books you check out. Which inequality represents this limit?
$b\le 6$
$b<6$
$b>6$
$b\ge 6$
Explanation
This question tests writing inequalities like b ≤ c from constraints, understanding infinite solutions though contextually discrete, with inclusive symbols for maximums. Words to symbols: 'maximum' means ≤ (includes: b ≤ 6 up to 6), similar to 'at most'; infinite in theory but books are integers 0 to 6. Example: 'maximum 6 books' → b ≤ 6, solutions: 0,1,2,3,4,5,6 (finite integers, but conceptually infinite if fractions allowed, though not). Correct is b ≤ 6, matching choice C. Error: using <6 excluding 6, or >6 reversing, or claiming no infinite solutions when reals ≤6 are infinite. Writing: (1) identify 'maximum' as inclusive lesser, (2) to ≤, (3) b ≤ 6; graphing would be ● at 6 shaded left. Infinite solutions technically all reals ≤6, but context integers; mistakes: wrong symbol (≤ vs <), reversal.
A science fair poster must be at least 36 inches wide. Let $w$ be the width (in inches). Which number line matches the solutions for $w$?
Closed circle at 36, shaded to the left
Open circle at 36, shaded to the right
Open circle at 36, shaded to the left
Closed circle at 36, shaded to the right
Explanation
This question tests writing inequalities like $w > c$ or $w < c$ from real-world constraints, understanding that they have infinitely many solutions, and representing them on number lines with proper boundary markers (● for included, ○ for excluded) and shading. Constraint words translate to symbols: 'at least' means ≥ (includes boundary, like $w \geq 36$ allows 36 or more), 'at most' means ≤ (includes), 'more than' means > (excludes), 'less than' means < (excludes); inequalities have infinite solutions unlike equations, and on a number line, use closed ● for ≥/≤, open ○ for >/<, shading right for greater and left for lesser. For example, 'at least 36' gives $w \geq 36$ with ● at 36 shaded right, infinite solutions. The correct number line is closed circle at 36 shaded right. A common error is open circle, excluding 36. For graphing: (1) mark 36, (2) closed ●, (3) shade right. Infinite solutions: all ≥36; mistakes include wrong circle or direction.
A school club requires members to be at least 13 years old. Let $a$ be a student's age (in years). Which inequality correctly represents this rule?
$a<13$
$a>13$
$a\ge 13$
$a\le 13$
Explanation
This question tests writing inequalities like a > c or a ≥ c from real-world constraints, understanding that inequalities have infinitely many solutions, and representing them on number lines with proper boundary markers such as closed circles (●) for inclusive or open circles (○) for exclusive, along with shading in the correct direction. Constraint words translate to symbols: 'at least' means ≥ which includes the boundary (a ≥ 13 means 13 or more), 'at most' means ≤ which includes it, 'more than' means > which excludes the boundary, and 'less than' means < which excludes it; inequalities have infinite solutions since they are satisfied by infinitely many numbers, unlike equations with finite solutions. For example, 'must be at least 13 years old' translates to a ≥ 13 where a is age, with solutions like 13, 14, 15, and infinitely many more, graphed as a number line with a closed circle at 13 and shading to the right (●======>). The correct inequality here is a ≥ 13, which includes 13 and all greater ages, matching choice B. A common error is using > instead of ≥ for 'at least,' excluding 13 incorrectly, or reversing to < or ≤, or misunderstanding infinite solutions by thinking only whole numbers count when actually all real numbers ≥13 satisfy it. To write this: (1) identify 'at least' as inclusive greater, (2) translate to ≥, (3) write a ≥ 13. For graphing: (1) draw number line, (2) mark 13, (3) use closed ● for ≥, (4) shade right for greater values; remember infinite solutions include all reals ≥13, and in context, ages like 13.5 would theoretically satisfy though practically ages are whole; mistakes include wrong symbol or circle type.
A game app requires your device to have more than 2 GB of free space. Let $g$ be the free space (in GB). Which inequality is correct?
$g<2$
$g\ge 2$
$g\le 2$
$g>2$
Explanation
This question tests writing inequalities like g > c or g < c from real-world constraints, understanding that they have infinitely many solutions, and representing them on number lines with proper boundary markers (● for included, ○ for excluded) and shading. Constraint words translate to symbols: 'at least' means ≥ (includes), 'at most' means ≤ (includes), 'more than' means > (excludes boundary, like g > 2 allows above 2 but not 2), 'less than' means < (excludes); inequalities have infinite solutions unlike equations, and on a number line, use closed ● for ≥/≤, open ○ for >/<, shading right for greater and left for lesser. For example, 'more than 2' gives g > 2 with infinite solutions like 2.1, 3, .... The correct inequality is g > 2. A common error is using ≥, including 2 wrongly. To write: (1) identify 'more than' as >, (2) translate to g > 2. Infinite solutions: all >2; mistakes like confusing with at least (≥).
Jordan is buying snacks and wants to spend at most $50. Let $x$ be the total cost (in dollars). Which inequality represents this situation?
$x\ge 50$
$x>50$
$x\le 50$
$x<50$
Explanation
This question tests writing inequalities like x > c or x < c from real-world constraints, understanding that they have infinitely many solutions, and representing them on number lines with proper boundary markers (● for included, ○ for excluded) and shading. Constraint words translate to symbols: 'at least' means ≥ (includes boundary, like x ≥ 10 allows 10 or more), 'at most' means ≤ (includes, like x ≤ 50 allows 50 or less), 'more than' means > (excludes), 'less than' means < (excludes); inequalities have infinite solutions unlike equations, and on a number line, use closed ● for ≥/≤, open ○ for >/<, shading right for greater and left for lesser. For example, 'score more than 75' gives x > 75 with solutions like 76, 77, ... infinitely many, graphed as ○ at 75 shaded right. The correct inequality is x ≤ 50, as 'at most 50' includes up to 50. A common error is using < instead of ≤, excluding 50, or reversing to ≥ thinking of minimum. To write it: (1) identify 'at most' as ≤, (2) translate to x ≤ 50. Infinite solutions: all reals ≤ 50; mistakes include confusing at most with more than or wrong symbol.
To earn a badge in a video game, you must score more than 75 points. Let $s$ be your score. Which inequality represents all possible scores that earn the badge?
$s\le 75$
$s>75$
$s<75$
$s\ge 75$
Explanation
This question tests writing inequalities like s > c from real-world constraints, recognizing infinitely many solutions, and the difference in symbols for exclusive vs inclusive boundaries. Constraint words to symbols: 'more than' → > (excludes boundary: s > 75 means above 75, not 75), 'at least' → ≥ (includes), 'less than' → <, 'at most' → ≤; infinite solutions as s > 75 includes 75.1, 76, ..., forever. For example, 'score more than 75' → s > 75, solutions: 76, 77, ... infinite integers or reals, graph: open ○ at 75 shaded right (○======>). The correct inequality is s > 75, matching choice C. Errors include using ≥ instead of >, including 75 wrongly, or reversing to <75, or saying finite solutions like only up to 100. Writing: (1) identify 'more than' as exclusive greater, (2) translate to >, (3) write s > 75; graphing would be open ○ at 75, shade right. Infinite solutions: uncountably many reals >75; context: scores above 75 qualify; mistakes: symbol mix-up (> vs ≥), not recognizing infinity.
A theme park ride requires riders to be at least 48 inches tall. Let $h$ be a rider's height in inches. Which value is a solution to the inequality?
$h=30$
$h=47$
$h=48$
$h=0$
Explanation
This question tests writing inequalities like x > c or x < c from real-world constraints, understanding infinitely many solutions, and representing on number lines with proper boundary markers (●/○) and shading. Constraint words translate to symbols: 'at least' → ≥ (includes boundary: x ≥ 10 means 10 or more), 'at most' → ≤ (includes: x ≤ 50 means 50 or less), 'more than' → > (excludes boundary: x > 75 means above 75, not including 75), 'less than' → < (excludes: x < 60 below 60); inequalities have infinitely many solutions (x > 10 includes 11, 12, 13, ..., 1000, ...—continues forever, unlike equations with one solution); on a number line, mark boundary at c (for x > 10, mark 10), use closed ● if ≥ or ≤ (includes), open ○ if > or < (excludes), shade right for > / ≥ (greater values), left for < / ≤ (lesser values). For example, 'must have at least 10 tickets' → x ≥ 10 (x = tickets, 10 or more), solutions: 10, 11, 12, ... infinitely many (all non-negative integers ≥ 10), graph: ● at 10 shaded right (●======> ), includes 10 and all greater; or 'score more than 75' → x > 75 (above 75, excludes 75), graph: ○======> at 75 (open circle, shade right), solutions: 76, 77, 78, ... infinite. The correct solution is h = 48 (choice B), as h ≥ 48 includes 48 and taller. Errors are values below 48 like 47, 30, or 0 (choices A, C, D), not satisfying ≥ 48. To check: (1) identify 'at least' as ≥, (2) write h ≥ 48, (3) test values (48 works, 47 does not). Infinite solutions: all reals ≥ 48; mistakes treat it as > or pick non-solutions.