12 multiple-choice questions, progressively harder.
Points AAA, BBB, and CCC occur in that order on a line. In one unit, AB=3x−2AB=3x-2AB=3x−2, BC=x+10BC=x+10BC=x+10, and AC=6xAC=6xAC=6x. What is BCBCBC?
Solution
Correct answer: A
Segment addition gives (3x−2)+(x+10)=6x(3x-2)+(x+10)=6x(3x−2)+(x+10)=6x. Thus 4x+8=6x4x+8=6x4x+8=6x, so x=4x=4x=4.
BC=4+10=14BC=4+10=14BC=4+10=14
The other part is 101010 and the whole is 242424, so the positive lengths check: 10+14=2410+14=2410+14=24.
On a line, MMM is the midpoint of AC‾\overline{AC}AC and BBB is between AAA and MMM. If AC=40AC=40AC=40 and AB=13AB=13AB=13, what is BMBMBM?
Correct answer: C
The midpoint gives AM=40/2=20AM=40/2=20AM=40/2=20. Point BBB splits that half into ABABAB and BMBMBM.
BM=20−13=7BM=20-13=7BM=20−13=7
The midpoint coordinate of JK‾\overline{JK}JK is 555, and JJJ has coordinate −14-14−14. What is JKJKJK?
Correct answer: B
The distance from JJJ to the midpoint is 5−(−14)=195-(-14)=195−(−14)=19. The whole segment has two equal halves.
JK=2(19)=38JK=2(19)=38JK=2(19)=38
Point PPP has coordinate −2-2−2, and QQQ lies on the same number line. Segment PQ‾\overline{PQ}PQ has length 888. Which is the complete list of possible midpoint coordinates?
Correct answer: D
The other endpoint can be −10-10−10 or 666. Half the segment length is 444, so the midpoint is four units to either side of PPP.
−2−4=−6-2-4=-6−2−4=−6
−2+4=2-2+4=2−2+4=2
Point MMM is the midpoint of AB‾\overline{AB}AB. A line through MMM intersects the segment only at MMM. If AB=2x+12AB=2x+12AB=2x+12 and AM=3x−4AM=3x-4AM=3x−4, what is ABABAB?
The whole length is twice a midpoint half: 2x+12=2(3x−4)2x+12=2(3x-4)2x+12=2(3x−4). Expanding gives 2x+12=6x−82x+12=6x-82x+12=6x−8, so x=5x=5x=5.
AB=2(5)+12=22AB=2(5)+12=22AB=2(5)+12=22
The half length is 3(5)−4=113(5)-4=113(5)−4=11, as required.
A segment has endpoints at −11-11−11 and 191919. A line crosses it at coordinate 444. What is the correct classification?
The crossing coordinate equals the average of the endpoints.
−11+192=4\frac{-11+19}{2}=42−11+19=4
It is therefore the midpoint. Passing through it establishes bisection, while the crossing angle remains unspecified.
Points RRR, SSS, TTT, and UUU occur in that order on a line. If RS=4.2RS=4.2RS=4.2 cm, ST=35ST=35ST=35 mm, and TU=1.3TU=1.3TU=1.3 cm, what is RURURU?
Convert 353535 millimeters to 3.53.53.5 centimeters. Then add all three adjacent lengths.
RU=4.2+3.5+1.3=9 cmRU=4.2+3.5+1.3=9\text{ cm}RU=4.2+3.5+1.3=9 cm
Point BBB is between AAA and CCC. The lengths satisfy AB=2BCAB=2BCAB=2BC and AC=45AC=45AC=45. What is ABABAB?
Let BC=tBC=tBC=t. Then AB=2tAB=2tAB=2t, and segment addition gives 2t+t=452t+t=452t+t=45, so t=15t=15t=15.
AB=2(15)=30AB=2(15)=30AB=2(15)=30
A segment's endpoints align with the 232323 mm and 797979 mm marks on a ruler. Which pair gives the readings that its midpoint would align with in millimeters and centimeters?
The midpoint reading is the average of the endpoint readings.
23+792=51 mm\frac{23+79}{2}=51\text{ mm}223+79=51 mm
This coordinate is 5.15.15.1 centimeters.
Half the length is 282828 millimeters, but that is not the midpoint's reading because the segment starts at 232323 millimeters.
Distinct points occur in order AAA, BBB, CCC, DDD. Point BBB is the midpoint of AC‾\overline{AC}AC, and CCC is the midpoint of BD‾\overline{BD}BD. If AB=6.5AB=6.5AB=6.5, what is ADADAD?
The first midpoint makes AB=BCAB=BCAB=BC. The second makes BC=CDBC=CDBC=CD. All three adjacent parts therefore have length 6.56.56.5.
AD=6.5+6.5+6.5=19.5AD=6.5+6.5+6.5=19.5AD=6.5+6.5+6.5=19.5
A segment is drawn with a line crossing it at a marked square corner. No length labels or congruence marks are provided. Which claim is justified?
The square-corner mark gives perpendicularity. No given information says the crossing point is the midpoint, so equal halves and bisection do not follow.
A number-line segment has midpoint −3-3−3 and length 141414. Which pair gives its endpoint coordinates?
Each endpoint is half the length, or 777 units, from the midpoint.
−3−7=−10-3-7=-10−3−7=−10
−3+7=4-3+7=4−3+7=4
Their distance is 141414 and their average is −3-3−3.
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