Yesterday, thousands of middle school and high school students participated in this year’s AMC 10A and 12A Competition (including some students at Areteem Headquarters seen below).

The problems can now be discussed! See below for answer keys for both the 2020 AMC 10A and AMC 12A questions as well as the concepts tested on each problem.

AMC 10A Answers

1

E

algebra: linear equations with fractions

2

C

averages and means

3

A

algebra: factoring and simplifying linear fractions

4

E

algebra: motion and rates

5

C

algebra: quadratic equations and absolute values

6

B

combinatorics: counting digits and divisibility

7

C

magic squares, arithmetic sequences, and averages

8

B

sequences and patterns, arithmetic series

9

B

number theory: least common multiples

10

B

geometry: solid geometry and surface area of cubes

11

C

medians and arithmetic

12

C

geometry: triangles and medians, areas

13

B

combinatorics: total probability and symmetry

14

D

algebra: factoring and Vieta’s formulas

15

E

number theory: number of factors and square factors, probability

16

B

probability: geometric probability, cases

17

E

algebra: polynomials and graphs, patterns

18

C

combinatorics: cases and parity

19

E

combinatorics: geometric paths and logic

20

D

geometry: right triangles, similar triangles, and area

21

C

algebra: geometric sequences and factoring

22

A

number theory: floor function and factors

23

A

geometry: composing transformations

24

C

number theory: GCDs and remainders

25

A

combinatorics: probability and logic

AMC 12A Answers

1

C

fractions and percentages

2

C

geometry: distance formula and length

3

E

algebra: motion and rates

4

B

combinatorics: counting digits and divisibility

5

C

magic squares, arithmetic sequences, and averages

6

D

geometry: symmetry in a rectangle

7

B

geometry: solid geometry and surface area of cubes

8

C

medians and arithmetic

9

E

algebra: graphs of trigonometric functions

10

E

algebra: rules of logarithms

11

B

combinatorics: total probability and symmetry

12

B

geometry: coordinates and rotations

13

B

algebra: exponents and radicals

14

B

geometry: octagon and triangle areas

15

D

algebra: complex roots and polar form

16

B

probability: geometric probability, cases

17

D

algebra and geometry: logarithms and coordinate areas

18

D

geometry: right triangles, similar triangles, and area

19

C

algebra: geometric sequences and factoring

20

A

geometry: composing transformations

21

D

number theory: primes and factors

22

B

algebra: complex numbers and sequences

23

A

combinatorics: probability and logic

24

B

geometry: triangles and rotations

25

C

algebra: floor function and solving quadratic equations

In total 11 questions appeared on both the AMC 10A and AMC 12A. They are listed below:

AMC 10A

AMC 12A

4

3

6

4

7

5

10

7

11

8

13

11

16

16

20

18

21

19

23

20

25

23

Need to see all the problems and solutions? Areteem’s Dr. Kevin Wang has you covered, solving all 39 problems and giving problem solving tips in a review video. Click here for more information and to purchase. As a limited time offer, we’re giving the video out for free through social media. Check them out for instructions! The problems are available as a free download by clicking here.

The AMC 10 and 12 exams are administered by the Mathematical Association of America (MAA). For general information about the AMC 10 and 12, click here.