Math Problem Statement

Next week your math teacher is giving a unit test. The test will consist of 18 questions. Some questions are worth 2 points and some questions are worth 3 points. The test is worth 43 total points. Write and solve a system of equations to determine how many 3-point questions are on the test.

Solution

Let's define variables and write a system of equations based on the given information:

  • Let xx be the number of 2-point questions.
  • Let yy be the number of 3-point questions.

We have two key pieces of information:

  1. The total number of questions is 18: x+y=18x + y = 18

  2. The total number of points is 43: 2x+3y=432x + 3y = 43

Solving the System:

Step 1: Solve for xx in terms of yy

From the first equation: x=18yx = 18 - y

Step 2: Substitute into the second equation

2(18y)+3y=432(18 - y) + 3y = 43

362y+3y=4336 - 2y + 3y = 43

36+y=4336 + y = 43

y=7y = 7

Step 3: Find xx

x=187=11x = 18 - 7 = 11

Answer:

  • There are 11 two-point questions.
  • There are 7 three-point questions.

Would you like a step-by-step explanation or have any questions?

Here are five related problems you might find interesting:

  1. What if the test had 20 questions and was worth 50 points? How would the system change?
  2. How many total points would be on a test with 25 questions, given the same scoring scheme?
  3. If there were 10 three-point questions, how many two-point questions would there be?
  4. Can you solve the system graphically? What would the intersection point represent?
  5. How would the system change if the two-point questions were instead worth 4 points?

Tip:

When solving a system of equations, substitution works well when one equation is easily solved for a variable, while elimination is useful when coefficients align nicely!

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Math Problem Analysis

Mathematical Concepts

Algebra
Systems of Equations

Formulas

x + y = 18
2x + 3y = 43

Theorems

Substitution Method
Linear Equations

Suitable Grade Level

Grades 7-9