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Finding the Fourth Proportional to 261.24, 391.89 and 87.90

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Solution

The fourth proportional to 261.24, 391.89 and 87.90 is: 131.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.24 : 391.89 = 87.90 : x
  2. Step 2: Convert to fraction form
    261.24/391.89 = 87.90/x
  3. Step 3: Cross multiply
    261.24x = 391.89 × 87.90
  4. Step 4: Simplify right side
    261.24x = 34,447.13
  5. Step 5: Solve for x
    x = 34,447.13/261.24
  6. Step 6: Final answer
    x = 131.86

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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.