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2009 AMC 10B · #1Linear Equations & Word Problems

Each morning of her five-day workweek, Jane bought either a 5050 -cent muffin or a 7575 -cent bagel. Her total cost for the week was a whole number of dollars. How many bagels did she buy?

2009 AMC 10B · #2Fractions & Decimals

Which of the following is equal to 13141213\dfrac{\frac{1}{3}-\frac{1}{4}}{\frac{1}{2}-\frac{1}{3}} ?

2009 AMC 10B · #3Ratios, Percents & Averages

Paula the painter had just enough paint for 3030 identically sized rooms. Unfortunately, on the way to work, three cans of paint fell off her truck, so she had only enough paint for 2525 rooms. How many cans of paint did she use for the 2525 rooms?

2009 AMC 10B · #4Quadrilaterals & Polygon Areas

A rectangular yard contains two flower beds in the shape of congruent isosceles right triangles. The remainder of the yard has a trapezoidal shape, as shown. The parallel sides of the trapezoid have lengths 1515 and 2525 meters. What fraction of the yard is occupied by the flower beds?

2009 AMC 10B · #5Ratios, Percents & Averages

Twenty percent less than 60 is one-third more than what number?

2009 AMC 10B · #6Divisibility & Factors

Kiana has two older twin brothers. The product of their three ages is 128. What is the sum of their three ages?

2009 AMC 10B · #7Basic Counting

By inserting parentheses, it is possible to give the expression 2×3+4×52\times3 + 4\times5 several values. How many different values can be obtained?

2009 AMC 10B · #8Ratios, Percents & Averages

In a certain year the price of gasoline rose by 20%20\% during January, fell by 20%20\% during February, rose by 25%25\% during March, and fell by x%x\% during April. The price of gasoline at the end of April was the same as it had been at the beginning of January. To the nearest integer, what is xx ?

2009 AMC 10B · #9Angles & Polygons

Segment BDBD and AEAE intersect at CC , as shown, AB=BC=CD=CEAB=BC=CD=CE , and A=52B\angle A = \frac 52 \angle B . What is the degree measure of D\angle D ?

2009 AMC 10B · #10Triangles: Area & Pythagorean

A flagpole is originally 55 meters tall. A hurricane snaps the flagpole at a point xx meters above the ground so that the upper part, still attached to the stump, touches the ground 11 meter away from the base. What is xx ?

2009 AMC 10B · #11Basic Counting

How many 77 -digit palindromes (numbers that read the same backward as forward) can be formed using the digits 22 , 22 , 33 , 33 , 55 , 55 , 55 ?

2009 AMC 10B · #12Triangles: Area & Pythagorean

Distinct points AA , BB , CC , and DD lie on a line, with AB=BC=CD=1AB=BC=CD=1 . Points EE and FF lie on a second line, parallel to the first, with EF=1EF=1 . A triangle with positive area has three of the six points as its vertices. How many possible values are there for the area of the triangle?

2009 AMC 10B · #13Modular Arithmetic

As shown below, convex pentagon ABCDEABCDE has sides AB=3AB=3 , BC=4BC=4 , CD=6CD=6 , DE=3DE=3 , and EA=7EA=7 . The pentagon is originally positioned in the plane with vertex AA at the origin and vertex BB on the positive xx -axis. The pentagon is then rolled clockwise to the right along the xx -axis. Which side will touch the …

2009 AMC 10B · #14Sequences & Series

On Monday, Millie puts a quart of seeds, 25%25\% of which are millet, into a bird feeder. On each successive day she adds another quart of the same mix of seeds without removing any seeds that are left. Each day the birds eat only 25%25\% of the millet in the feeder, but they eat all of the other seeds. On which day, …

2009 AMC 10B · #15Linear Equations & Word Problems

When a bucket is two-thirds full of water, the bucket and water weigh aa kilograms. When the bucket is one-half full of water the total weight is bb kilograms. In terms of aa and bb , what is the total weight in kilograms when the bucket is full of water?

2009 AMC 10B · #16Circles

Points AA and CC lie on a circle centered at OO , each of BA\overline{BA} and BC\overline{BC} are tangent to the circle, and ABC\triangle ABC is equilateral. The circle intersects BO\overline{BO} at DD . What is BDBO\frac{BD}{BO} ?

2009 AMC 10B · #17Coordinate Geometry

Five unit squares are arranged in the coordinate plane as shown, with the lower left corner at the origin. The slanted line, extending from (c,0)(c,0) to (3,3)(3,3) , divides the entire region into two regions of equal area. What is cc ?

2009 AMC 10B · #18Similar & Congruent Triangles

Rectangle ABCDABCD has AB=8AB=8 and BC=6BC=6 . Point MM is the midpoint of diagonal AC\overline{AC} , and EE is on ABAB with MEAC\overline{ME}\perp\overline{AC} . What is the area of AME\triangle AME ?

2009 AMC 10B · #19Basic Counting

A particular 1212 -hour digital clock displays the hour and minute of a day. Unfortunately, whenever it is supposed to display a 11 , it mistakenly displays a 99 . For example, when it is 1:16 PM the clock incorrectly shows 9:96 PM. What fraction of the day will the clock show the correct time?

2009 AMC 10B · #20Triangle Centers & Cevians

Triangle ABCABC has a right angle at BB , AB=1AB=1 , and BC=2BC=2 . The angle bisector of A\angle A intersects side BC\overline{BC} at DD . What is BDBD ?

2009 AMC 10B · #21Modular Arithmetic

What is the remainder when 30+31+32++320093^0 + 3^1 + 3^2 + \cdots + 3^{2009} is divided by 8?

2009 AMC 10B · #22Solid Geometry

A cubical cake with edge length 22 inches is iced on the sides and the top. It is cut vertically into three pieces as shown in this top view, where MM is the midpoint of a top edge. The piece whose top is triangle BB contains cc cubic inches of cake and ss square inches of icing. What is c+sc+s ?

2009 AMC 10B · #23Geometric Probability

Rachel and Robert run on a circular track. Rachel runs counterclockwise and completes a lap every 90 seconds, and Robert runs clockwise and completes a lap every 80 seconds. Both start from the same line at the same time. At some random time between 10 minutes and 11 minutes after they begin to run, a photographer …

2009 AMC 10B · #24Angles & Polygons

The keystone arch is an ancient architectural feature. It is composed of congruent isosceles trapezoids fitted together along the non-parallel sides, as shown. The bottom sides of the two end trapezoids are horizontal. In an arch made with 99 trapezoids, let xx be the angle measure in degrees of the larger interior …

2009 AMC 10B · #25Basic Probability

Each face of a cube is given a single narrow stripe painted from the center of one edge to the center of the opposite edge. The choice of the edge pairing is made at random and independently for each face. What is the probability that there is a continuous stripe encircling the cube?

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