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Finding the Fourth Proportional to 87.57, 120.65 and 65.61

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Solution

The fourth proportional to 87.57, 120.65 and 65.61 is: 90.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.57 : 120.65 = 65.61 : x
  2. Step 2: Convert to fraction form
    87.57/120.65 = 65.61/x
  3. Step 3: Cross multiply
    87.57x = 120.65 × 65.61
  4. Step 4: Simplify right side
    87.57x = 7,915.52
  5. Step 5: Solve for x
    x = 7,915.52/87.57
  6. Step 6: Final answer
    x = 90.39

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.