MathDB

Problems(6)

1999 Advanced Topics #2: Stacy Goes Shopping

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6/21/2012
Stacy has dd dollars. She enters a mall with 1010 shops and a lottery stall. First she goes to the lottery and her money is doubled, then she goes into the first shop and spends 10241024 dollars. After that she alternates playing the lottery and getting her money doubled (Stacy always wins) then going into a new shop and spending $1024\$1024. When she comes out of the last shop she has no money left. What is the minimum possible value of dd?
1999 Algebra #2: Positive Integer That Divides Into 91

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6/21/2012
For what single digit nn does 9191 divide the 99-digit number 12345n78912345n789?
modular arithmetic
1999 Calculus #2: Sides of a Rectangle

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6/21/2012
A rectangle has sides of length sinx\sin x and cosx\cos x for some xx. What is the largest possible area of such a rectangle?
calculusgeometryrectangletrigonometry
1999 HMMT Geometry # 2

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3/3/2024
A semicircle is inscribed in a semicircle of radius 22 as shown. Find the radius of the smaller semicircle. https://cdn.artofproblemsolving.com/attachments/c/1/c60cd40eaecfe417aca46ce4fd386fe22af85b.png
geometry
a ladder is leaning against a house 1999 HMMT Team 2

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1/1/2022
A ladder is leaning against a house with its lower end 1515 feet from the house. When the lower end is pulled 99 feet farther from the house, the upper end slides 1313 feet down. How long is the ladder (in feet)?
geometryright triangle
1999 Oral #2: Allergic Reactions

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10/20/2012
Alex, Pei-Hsin, and Edward got together before the contest to send a mailing to all the invited schools. Pei-Hsin usually just stu ffs the envelopes, but if Alex leaves the room she has to lick them as well and has a 25%25\% chance of dying from an allergic reaction before he gets back. Licking the glue makes Edward a bit psychotic, so if Alex leaves the room there is a 20%20\% chance that Edward will kill Pei-Hsin before she can start licking envelopes. Alex leaves the room and comes back to fi nd Pei-Hsin dead. What is the probability that Edward was responsible?
probability