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Finding the Fourth Proportional to 87.76, 121.12 and 56.66

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Solution

The fourth proportional to 87.76, 121.12 and 56.66 is: 78.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    87.76 : 121.12 = 56.66 : x
  2. Step 2: Convert to fraction form
    87.76/121.12 = 56.66/x
  3. Step 3: Cross multiply
    87.76x = 121.12 × 56.66
  4. Step 4: Simplify right side
    87.76x = 6,862.66
  5. Step 5: Solve for x
    x = 6,862.66/87.76
  6. Step 6: Final answer
    x = 78.20

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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.