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Finding the Fourth Proportional to 261.25, 391.96 and 87.91

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Solution

The fourth proportional to 261.25, 391.96 and 87.91 is: 131.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    261.25 : 391.96 = 87.91 : x
  2. Step 2: Convert to fraction form
    261.25/391.96 = 87.91/x
  3. Step 3: Cross multiply
    261.25x = 391.96 × 87.91
  4. Step 4: Simplify right side
    261.25x = 34,454.80
  5. Step 5: Solve for x
    x = 34,454.80/261.25
  6. Step 6: Final answer
    x = 131.89

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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.