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Finding the Fourth Proportional to 72.78, 100.54 and 56.61

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Solution

The fourth proportional to 72.78, 100.54 and 56.61 is: 78.20

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.78 : 100.54 = 56.61 : x
  2. Step 2: Convert to fraction form
    72.78/100.54 = 56.61/x
  3. Step 3: Cross multiply
    72.78x = 100.54 × 56.61
  4. Step 4: Simplify right side
    72.78x = 5,691.29
  5. Step 5: Solve for x
    x = 5,691.29/72.78
  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.