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Finding the Fourth Proportional to 100.92, 139.28 and 56.66

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Solution

The fourth proportional to 100.92, 139.28 and 56.66 is: 78.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    100.92 : 139.28 = 56.66 : x
  2. Step 2: Convert to fraction form
    100.92/139.28 = 56.66/x
  3. Step 3: Cross multiply
    100.92x = 139.28 × 56.66
  4. Step 4: Simplify right side
    100.92x = 7,891.64
  5. Step 5: Solve for x
    x = 7,891.64/100.92
  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.