math-eval/TAL-SCQ5K huggingface dataset:
Problem: Gary will be three times as old as Harry $$4$$ years from now. If Harry is $$5$$ years old now, how old will Gary be in $$4$$ years? 
Options:
aoVal: A
content: $$10$$ 
aoVal: B
content: $$23$$ 
aoVal: C
content: $$27$$ 
aoVal: D
content: $$31$$ 
aoVal: E
content: $$36$$ 
Answer: C
Analysis: Harry is $$5$$ years old now; he\textquotesingle ll be $$9$$ in $$4$$ years.  Gary is thus $$3\times9=27$$ years old 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Age Problems->Basic Relationships in Age Problems
Problem: Bowen has $$40$$ grams of a $$25\textbackslash\%$$ sugar solution. After~\uline{~~~~~~~~~~}~of water evaporates, the percent concentration of the solution is $$40\textbackslash\%$$. (Evaporate: the water turns from liquid into vapor and is no longer in the solution anymore.) 
Options:
aoVal: A
content: $$15$$ grams 
aoVal: B
content: $$12$$ grams 
aoVal: C
content: $$9$$ grams 
aoVal: D
content: $$6$$ grams 
Answer: A
Analysis: $$40-40\times25\textbackslash\%\div40\textbackslash\%=40-25=15$$ ounces. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Concentration Problems->Finding and Making Use of Invariants
Problem: Mike makes $5$ cakes every minute. He works for $16$ minutes. How many cakes does he make altogethe? 
Options:
aoVal: A
content: $$80$$ 
aoVal: B
content: $$90$$ 
aoVal: C
content: $$100$$ 
aoVal: D
content: $$70$$ 
Answer: A
Analysis: $$16\times 5 = 80$$  ~ 
Knowledge points: Overseas Competition->Knowledge Point->Distance Word Problems->Distance Word Problems on Straight Road
Problem: Luis has 7 apples and 2 bananas. He gives 2 apples to Yuri who, in return gives bananas to Luis. Then Luis has as many apples as bananas. How many bananas did Yuri give to Luis? 
Options:
aoVal: A
content: $$2$$ 
aoVal: B
content: $$3$$ 
aoVal: C
content: $$4$$ 
aoVal: D
content: $$5$$ 
aoVal: E
content: $$7$$ 
Answer: B
Analysis: $$7-2=5$$  $$5-2=3.$$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Applying Addition and Subtraction
Source: 其它
Problem: Alice\textquotesingle s first day in Caterpillar Club was Tuesday. She wants to throw a party on her 40th day in the club. If Alice attends the club everyday, on which day of the week will the party be? 
Options:
aoVal: A
content: Friday 
aoVal: B
content: Saturday 
aoVal: C
content: Sunday 
aoVal: D
content: Monday 
aoVal: E
content: None of the above 
Answer: B
Analysis: 40th day = 39th day after first day joining.  39 days/7 = 5 weeks R 4 days. 4 days after Tues is Saturday. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Periodic Problems->Periodic Problems of Time
Source: 其它
Problem: A fifth-grade class has $8$ boys and $10$ girls. What is the ratio of boys to girls?. 
Options:
aoVal: A
content: $8:10$ 
aoVal: B
content: $10:8$ 
aoVal: C
content: $4:5$ 
aoVal: D
content: $5:4$ 
Answer: C
Analysis: Simplify $8:10$ to $4:5$, or $\text{C}$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Proportions->Basic Units
Problem: Emily was $$6$$ years old last year, and her sister was $$6$$ years old six years ago. What is the age difference between Emily and her sister today? 
Options:
aoVal: A
content: $$4$$ 
aoVal: B
content: $$5$$ 
aoVal: C
content: $$7$$ 
aoVal: D
content: $$13$$ 
aoVal: E
content: $$14$$ 
Answer: B
Analysis: Emily was $$6$$ years old last year , which means Emily is $7$ years old this year. Her sister was~ $$6$$ years old six years ago, which tells us her sister is~ $12$ years old this year, so the age difference is $5$ today. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Age Problems->Basic Relationships in Age Problems->Difference of Ages
Problem: Gill is now 27 and has moved into a new flat. She has four pictures to hang in a horizontal row on a wall which is 4800 mm wide. The pictures are identical in size and are 420 mm wide. Gill hangs the first two pictures so that one is on the extreme left of the wall and one is on the extreme right of the wall. She wants to hang the remaining two pictures so that all four pictures are equally spaced. How far should Gill place the centre of each of the two remaining pictures from a vertical line down the centre of the wall? 
Options:
aoVal: A
content: $$210mm$$ 
aoVal: B
content: $$520mm$$ 
aoVal: C
content: $$730mm$$ 
aoVal: D
content: $$840mm$$ 
aoVal: E
content: $$1040mm$$ 
Answer: C
Analysis: omitted 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Interval Problems
Source: 其它
Problem: David and Billy are on the bus together. They sit in the same column. There are $5$ people in front of David, Billy is in the middle. There are $10$ people behind Billy, and David is in the middle. How many people in this column? (adapted from2004 Math Kangaroo Problem, Level 3 - 4, Question \#19) 
Options:
aoVal: A
content: $$14$$ 
aoVal: B
content: $$13$$ 
aoVal: C
content: $$12$$ 
aoVal: D
content: $$11$$ 
aoVal: E
content: $$10$$ 
Answer: B
Analysis: $5 + 10 - 2 = 13$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Problems Involving Queuing->Finding the Total Number According to the Position of Two Characters in a Line
Problem: How many pieces can we get if we break a wooden stick in $8$ places? (Adapted from 1999 Math Kangaroo Problem, Level 3-4, Question \#3) 
Options:
aoVal: A
content: $$6$$ 
aoVal: B
content: $$7$$ 
aoVal: C
content: $$8$$ 
aoVal: D
content: $$9$$ 
aoVal: E
content: $$16$$ 
Answer: D
Analysis: $8+1=9$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Interval Problems->Planting no Trees on either Side (straight line type)->Sawing Woods
Source: 其它
Problem: There were $$27$$ children in a class.  There were twice as many boys as girls.  How many boys were there? 
Options:
aoVal: A
content: $$21$$ boys 
aoVal: B
content: $$18$$ boys 
aoVal: C
content: $$16$$ boys 
aoVal: D
content: $$14$$ boys 
aoVal: E
content: $$9$$ boys 
Answer: B
Analysis: $$\dfrac{27}{(2+1)}=9$$, $$9\times2=18$$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples->Problems of Sum and Multiple
Problem: There are twice as many boys in a room as girls. If $$5$$ boys leave the room, there would be an equal number of boys and girls in the room. How many boys were in the room at first? 
Options:
aoVal: A
content: $$5$$ 
aoVal: B
content: $$10$$ 
aoVal: C
content: $$15$$ 
aoVal: D
content: $$20$$ 
Answer: B
Analysis: The number of boys that leave the room must equal the number of boys that remain. Since $$5$$ boys leave, there are $$5$$ boys still in the room for a total of $$10$$ boys. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples->Problems of Difference and Multiple
Problem: There are twelve rooms in a building and each room has two windows and one light. Last evening, eighteen windows were lit. In how many rooms was the light off? (2016 Math Kangaroo Problem, Level 1-2, Question \#14) 
Options:
aoVal: A
content: $$2$$ 
aoVal: B
content: $$3$$ 
aoVal: C
content: $$4$$ 
aoVal: D
content: $$5$$ 
aoVal: E
content: $$6$$ 
Answer: B
Analysis: $18\div2=9$, $12-9=3$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Total Value using Unitary Method
Source: 其它
Problem: There were $$31$$ runners competing in a race. The number of runners who finished before John is $18$ less than the number of runners who finished later than John. At what place did John finish? (Adapted from 1998 Math Kangaroo Problem, Level 3 - 4, Question \#13) 
Options:
aoVal: A
content: $$6$$ 
aoVal: B
content: $$7$$ 
aoVal: C
content: $$8$$ 
aoVal: D
content: $$20$$ 
aoVal: E
content: $$21$$ 
Answer: B
Analysis: Before: $$(31-1-18) \div 2 = 6$$, and John: $$6+1=7$$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Questions Involving Sum, Difference and Multiples->Problems of Sum and Multiple
Problem: A basket with $$5$$ watermelons weighs $$3250$$ grams. If $$3$$ of the watermelons were taken out, the remaining weight would be $$1510$$ grams. What is the weight (in grams) of the basket? 
Options:
aoVal: A
content: $$350$$ grams 
aoVal: B
content: $$1160$$ grams 
aoVal: C
content: $$1740$$ grams 
aoVal: D
content: $$870$$ grams 
aoVal: E
content: None of the above 
Answer: A
Analysis: $$NA.$$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Equation Word Problems->Equivalent Substitution in Equation Word Problems->Replacement of Equivalent Substitution
Source: 其它
Problem: In a magic land, a monkey wants to climb a tree of $180$ m. The monkey can make one of the two kinds of climb each day: $6$ m up or $10$ m up. Beginning at the ground , at least how many days will the monkey need in order to rest on the branch of $108$ m high? 
Options:
aoVal: A
content: $$9$$ 
aoVal: B
content: $$10$$ 
aoVal: C
content: $$11$$ 
aoVal: D
content: $$12$$ 
aoVal: E
content: $$14$$ 
Answer: D
Analysis: $10 \times 9 + 6 \times 3 = 108$  $9 + 3 = 12$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Applying Addition and Subtraction->Problems Involving Extreme Value
Source: 其它
Problem: $4$ years gao, the sum of Cathy\textquotesingle s and Larry\textquotesingle s ages was $$20$$. What is the sum of their ages this years? 
Options:
aoVal: A
content: $$16$$ 
aoVal: B
content: $$28$$ 
aoVal: C
content: $$24$$ 
aoVal: D
content: $$36$$ 
aoVal: E
content: $$38$$ 
Answer: B
Analysis: $$20 + 4 + 4 = 28$$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules
Source: 其它
Problem: $$75$$ out of $$100$$ apples are \textbf{not} rotten. What percentage of the apples are rotten? 
Options:
aoVal: A
content: 75\% 
aoVal: B
content: 100\% 
aoVal: C
content: 25\% 
aoVal: D
content: 50\% 
aoVal: E
content: 175\% 
Answer: C
Analysis: $$\frac{75}{100}=75 \textbackslash\%$$,  $$100\textbackslash\%-75\textbackslash\%=25\textbackslash\%$$,  $$25\textbackslash\%$$ of the apples are rotten. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Finding the Rate
Problem: Find the exact number of minutes after $3.00 \text{pm}$ when the minute and hour hands are first at $90^{\circ}$ to each other. 
Options:
aoVal: A
content: $$31 \frac{2}{11}$$ 
aoVal: B
content: $$31 \frac{3}{11}$$ 
aoVal: C
content: $$32 \frac{8}{11}$$ 
aoVal: D
content: $$33 \frac{3}{11}$$ 
aoVal: E
content: None of the above 
Answer: C
Analysis: NA 
Knowledge points: Overseas Competition->Knowledge Point->Distance Word Problems->Clock Problems
Problem: How many times does it take to cut a rope into $$5$$ pieces? The rope can\textquotesingle t be folded. 
Options:
aoVal: A
content: $$3$$ 
aoVal: B
content: $$4$$ 
aoVal: C
content: $$5$$ 
aoVal: D
content: $$6$$ 
aoVal: E
content: It depends on how long the rope is. 
Answer: B
Analysis: $$5 - 1 = 4$$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Interval Problems
Source: 其它
Problem: Amy has $12$ candies and Nancy has $33$ candies. How many candies do they have in total? 
Options:
aoVal: A
content: $$21$$ 
aoVal: B
content: $$33$$ 
aoVal: C
content: $$44$$ 
aoVal: D
content: $$45$$ 
Answer: D
Analysis: $12+33=45$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules
Source: 其它
Problem: Paul was going to buy $$4$$ servings of ice cream, but he was $$80$$ pence short. So, he bought $$3$$ servings and had $$30$$ pence left. What was the price of one serving of ice cream? 
Options:
aoVal: A
content: $$70$$ pence 
aoVal: B
content: $$80$$ pence 
aoVal: C
content: $$90$$ pence 
aoVal: D
content: $$100$$ pence 
aoVal: E
content: 110 pence 
Answer: E
Analysis: $$(80+30)\div (4-3)=110$$ pence. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Distribution Problems->Basic Distribution Problems
Problem: Luke and Matthew ran a lemonade stand on Saturday. They agreed that Matthew would get $65$\% of the profit because the lemonade stand was his idea. They made a profit of $60$ dollars. How much money did Luke make? 
Options:
aoVal: A
content: $$21$$ 
aoVal: B
content: $$24$$ 
aoVal: C
content: $$36$$ 
aoVal: D
content: $$39$$ 
Answer: A
Analysis: $60 \times 65$\%=$39$,  $60-39=21$,  Luke made $21$ dollars. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Percentages Word Problems
Source: 其它
Problem: Alan is $5$ years old, his mother is $18$ years older than him, and his father is $2$ years older than his mother. How old is his father?~(adapted from $$2005$$ Math kangaroo Problems, Level $$1-2$$, Question \#$$7$$) 
Options:
aoVal: A
content: $$21$$ 
aoVal: B
content: $$25$$ 
aoVal: C
content: $$27$$ 
aoVal: D
content: $$28$$ 
aoVal: E
content: $$30$$ 
Answer: B
Analysis: Alans\textquotesingle{} mother is $18$ years older than him, his mother is $23$ years old.  His father is two years older than his mother, so he is $25$ years old. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Age Problems->Basic Relationships in Age Problems->Difference of Ages
Problem: On Monday morning, a snail fell down a well which is $$5$$ metres deep. During the day, it climbs up $$2$$ metres, and during the night it slides down $$1$$ metre. On what day of the week will the snail get out of the well? 
Options:
aoVal: A
content: $$$$Tuesday 
aoVal: B
content: $$$$Wednesday 
aoVal: C
content: $$$$Thursday 
aoVal: D
content: $$$$Friday 
aoVal: E
content: $$$$Monday 
Answer: C
Analysis: Nil 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Periodic Problems->Snail Climbing out of Well Problems->Snail Climbing out of Well (completed)
Problem: $$37$$ sakura trees were planted along one side of the road. The trees were planted at $$4m$$ intervals. After drivers complained the road was too pink, pineapple trees were planted on the other side of the road at $$6m$$ intervals. If there were sakura and pineapple trees at both ends of the road, how many pineapple trees were planted? ． 
Options:
aoVal: A
content: $$24$$ 
aoVal: B
content: $$25$$ 
aoVal: C
content: $$144$$ 
aoVal: D
content: $$18$$ 
Answer: B
Analysis: Number of sakura intervals = $$37-1 = 36$$  Length of road = $$36 \times 4 = 144m$$  Number of pineapple intervals = $$144m \div 6m = 24$$  Number of pineapple trees = $$24 + 1 = 25$$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Interval Problems
Source: 其它
Problem: Fatimah has $$3$$ bags of marbles. There are $$291$$ marbles in each bag. How many marbles does Fatimah have in all? 
Options:
aoVal: A
content: $$97$$ 
aoVal: B
content: $$294$$ 
aoVal: C
content: $$582$$ 
aoVal: D
content: $$873$$ 
Answer: D
Analysis: $$3\times291=873$$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Total Value using Unitary Method
Problem: I ate lunch every day of my $$12$$-week summer break. I ate lunch out-doors only on every Saturday, Sunday, and Tuesday. I ate lunch in-doors ondays. 
Options:
aoVal: A
content: $$24$$ 
aoVal: B
content: $$36$$ 
aoVal: C
content: $$48$$ 
aoVal: D
content: $$60$$ 
Answer: C
Analysis: I ate lunch every day of my $$12$$-week summer break. I ate lunch out-doors only on every Saturday, Sunday, and Tuesday. I ate lunch in-doors $$4$$ days each week. In $$12$$ weeks, that\textquotesingle s $$12\times 4=48$$ days. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Total Value using Unitary Method
Problem: Bella and her brother agreed to share a pizza which was cut into $15$ slices. Bella ate $40$\% of the pizza. How many slices did she eat? 
Options:
aoVal: A
content: $$4$$ 
aoVal: B
content: $$6$$ 
aoVal: C
content: $$9$$ 
aoVal: D
content: $$11$$ 
Answer: B
Analysis: $15 \times 40$\%=$6$,  She ate $6$ slices. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Percentages Word Problems
Source: 其它
Problem: In a jar of red, green, and blue marbles, all but $$6$$ are red marbles, all but $$8$$ are green, and all but $$4$$ are blue. How many marbles are in the jar? ． 
Options:
aoVal: A
content: $$6$$ 
aoVal: B
content: $$8$$ 
aoVal: C
content: $$9$$ 
aoVal: D
content: $$10$$ 
aoVal: E
content: $$12$$ 
Answer: C
Analysis: Suppose there are $$x$$ red marbles, $$y$$ green marbles and $$z$$ blue marbles. Thus, we can get  $$\begin{cases} x+y=4① \textbackslash\textbackslash{} y+z=6②\textbackslash\x+z=8③\end{cases}$$,  ①$$+$$②$$+$$③: $$2x+2y+2z=18$$, $$x+y+z=9$$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Equation Word Problems->Multivariate Linear Equation Word Problems
Problem: Cecilia and her dad are climbing stairs from the first floor. They start at the same time, and each of them keeps her or his speed of climbing unchanged. When Cecilia arrives at the third floor, her dad arrives at the fifth floor. When Cecilia arrives at the eighth floor, which floor does her dad arrive at? 
Options:
aoVal: A
content: $$14$$\textsuperscript{th} 
aoVal: B
content: $$15$$\textsuperscript{th} 
aoVal: C
content: $$10$$\textsuperscript{th} 
aoVal: D
content: $$13$$\textsuperscript{th} 
aoVal: E
content: $$16$$\textsuperscript{th} 
Answer: B
Analysis: $(5-1) \div(3-1)=2$. $(8-1) \times 2+1=15$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Interval Problems
Problem: After Sally takes 20 shots, she has made $50 \textbackslash\%$ of her shots. After she takes 5 more shots, she raises her percentage to $60 \textbackslash\%$. How many of the last 5 shots did she make? (adapted from 2004 AMC 8, Question\#6) 
Options:
aoVal: A
content: $$1$$ 
aoVal: B
content: $$2$$ 
aoVal: C
content: $$3$$ 
aoVal: D
content: $$4$$ 
aoVal: E
content: $$5$$ 
Answer: E
Analysis: Sally made $0.5\times 20=10$ shots originally. Letting $x$ be the number of shots she made, we have $\frac{10+x}{25}=0.60$. Solving for $x$ gives us $x=$ $(E)5$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Percentages Word Problems
Source: 其它
Problem: Irene mixes $$100$$ grams of dogfood that contains $$50\textbackslash\%$$ rice with $$400$$ grams of dogfood that contains $$80\textbackslash\%$$ rice. Find the percent concentration of the rice in the new mixture. 
Options:
aoVal: A
content: $$70\textbackslash\%$$ 
aoVal: B
content: $$72\textbackslash\%$$ 
aoVal: C
content: $$75\textbackslash\%$$ 
aoVal: D
content: $$74\textbackslash\%$$ 
Answer: D
Analysis: $$\dfrac{100\times50\textbackslash\%+400\times80\textbackslash\%}{100+400}=74\textbackslash\%$$. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Concentration Problems->Basic Concentration Problems
Problem: The average cost of a long-distance call in the USA in 1985 was 41 cents per minute, and the average cost of a long-distance call in the USA in 2005 was 7 cents per minute. Find the approximate percent decrease in the cost per minute of a long- distance call. (2007 AMC 8, Question \#6) 
Options:
aoVal: A
content: $$7$$ 
aoVal: B
content: $$17$$ 
aoVal: C
content: $$34$$ 
aoVal: D
content: $$41$$ 
aoVal: E
content: $$80$$ 
Answer: E
Analysis: The percent decrease is (the amount of decrease)/(original amount) the amount of decrease is $41-7=34$ so the percent decrease is $\frac{34}{41}$ which is about $(\mathbf{E}) 80 \textbackslash\%$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Percentages Word Problems
Source: 其它
Problem: Mike has $$160$$ grams of a $$3\textbackslash\%$$ salt solution and Danni has an $$8\textbackslash\%$$ salt solution. If Danni gives $$200$$ grams of her solution to Mike, they will have the same amount of pure salt in their solutions. How many grams of solution did Danni have in the beginning? 
Options:
aoVal: A
content: $400$ 
aoVal: B
content: $450$ 
aoVal: C
content: $460$ 
aoVal: D
content: $480$ 
Answer: C
Analysis: $$160\times3\textbackslash\%+200\times8\textbackslash\%=20.8$$ ounces.  $$20.8\div8\textbackslash\%+200=260+200=460$$ ounces. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Concentration Problems
Problem: At the 2017 King County Fair a vendor is offering a "fair special" on hats. If you buy one hat at the regular price of $40$ dollars, you get a second hat at a $10 \textbackslash\%$ discount, and a third pair at half the regular price. James took advantage of the "fair special" to buy three hats. What percentage of the $120$ dollars regular price did he save? (adapted from 2013 AMC 8, Question \#12) 
Options:
aoVal: A
content: $$15$$ 
aoVal: B
content: $$20$$ 
aoVal: C
content: $$25$$ 
aoVal: D
content: $$30$$ 
aoVal: E
content: $$40$$ 
Answer: B
Analysis: First, find the amount of money one will pay for three hats without the discount. We have $\textbackslash$ 40 \times 3$ hats $=\textbackslash$ 120$. Then, find the amount of money using the discount: $40+0.9 \times 40+\frac{1}{2} \times 40=\textbackslash$ 96$. Finding the percentage yields $\frac{96}{120}=80 \textbackslash\%$ To find the percent saved, we have $100 \textbackslash\%-80 \textbackslash\%=(\text{B}) 20$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Solving Problems Involving Fractions and Percentages->Percentages Word Problems
Source: 其它
Problem: My aunt can fold $$16$$ paper cranes in $$4$$ minutes. My uncle can fold $$15$$ paper cranes in $$5$$ minutes. How long would it take them to fold $$42$$ cranes if they work together at those rates?　 
Options:
aoVal: A
content: $$6$$ minutes 
aoVal: B
content: $$9$$ minutes 
aoVal: C
content: $$12$$ minutes 
aoVal: D
content: $$13$$ minutes 
Answer: A
Analysis: My aunt can fold $$4$$ paper cranes in $$1$$ minute. My uncle can fold 3 paper cranes in $$1$$ minute. Together they fold $$7$$ paper cranes in $$1$$ minute. It takes them $$42\div7 = 6$$ minutes to fold $$42$$ paper cranes. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Work Word Problems->Collaborative Work Word Problems
Problem: On the farm, there are $$5$$ sheep, $$5$$ hens, $$2$$ dogs, $$2$$ cats, and the farmer. How many legs are there altogether? (2006 Math Kangaroo Problem, Level 1-2, Question \#15) 
Options:
aoVal: A
content: $$20$$ 
aoVal: B
content: $$14$$ 
aoVal: C
content: $$24$$ 
aoVal: D
content: $$48$$ 
aoVal: E
content: $$46$$ 
Answer: D
Analysis: $5\times4+5\times2+2\times4+2\times4+2=48$ 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Unit Rate and then the Total Value
Problem: If $$11$$th November 2031 is a Tuesday, what day of the week will $$11$$th November 2032 be? 
Options:
aoVal: A
content: Tuesday 
aoVal: B
content: Wednesday 
aoVal: C
content: Thursday 
aoVal: D
content: Friday 
Answer: C
Analysis: $$1$$ leap year, so $$2$$ days shifted. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Periodic Problems->Periodic Problems of Time->Period of Dates
Source: 其它
Problem: An average of $$40$$ campers sign up for each of the $$6$$ sports at camp. If each camper signs up for exactly $$3$$ sports, how many campers are there? 
Options:
aoVal: A
content: $$80$$ 
aoVal: B
content: $$120$$ 
aoVal: C
content: $$160$$ 
aoVal: D
content: $$180$$ 
Answer: A
Analysis: Since $$40\times 6=240$$, $$240$$ campers have signed up for the $$6$$ sports, and each camper is counted $$3$$ times. There are $$240\div 3=80$$ campers in all. 
Knowledge points: Overseas Competition->Knowledge Point->Word Problem Modules->Unitary Method Problems->Finding the Total Value using Unitary Method