Home / 138.78-207.66-87.42

Finding the Fourth Proportional to 138.78, 207.66 and 87.42

Calculator

Solution

The fourth proportional to 138.78, 207.66 and 87.42 is: 130.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    138.78 : 207.66 = 87.42 : x
  2. Step 2: Convert to fraction form
    138.78/207.66 = 87.42/x
  3. Step 3: Cross multiply
    138.78x = 207.66 × 87.42
  4. Step 4: Simplify right side
    138.78x = 18,153.64
  5. Step 5: Solve for x
    x = 18,153.64/138.78
  6. Step 6: Final answer
    x = 130.81

Related Problems

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.