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Finding the Fourth Proportional to 87.69, 121.02 and 56.61

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Solution

The fourth proportional to 87.69, 121.02 and 56.61 is: 78.13

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.69 : 121.02 = 56.61 : x
  2. Step 2: Convert to fraction form
    87.69/121.02 = 56.61/x
  3. Step 3: Cross multiply
    87.69x = 121.02 × 56.61
  4. Step 4: Simplify right side
    87.69x = 6,850.94
  5. Step 5: Solve for x
    x = 6,850.94/87.69
  6. Step 6: Final answer
    x = 78.13

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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.