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Finding the Fourth Proportional to 87.86, 121.14 and 65.72

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Solution

The fourth proportional to 87.86, 121.14 and 65.72 is: 90.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.86 : 121.14 = 65.72 : x
  2. Step 2: Convert to fraction form
    87.86/121.14 = 65.72/x
  3. Step 3: Cross multiply
    87.86x = 121.14 × 65.72
  4. Step 4: Simplify right side
    87.86x = 7,961.32
  5. Step 5: Solve for x
    x = 7,961.32/87.86
  6. Step 6: Final answer
    x = 90.61

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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.