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Finding the Fourth Proportional to 78.72, 118.16 and 55.86

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Solution

The fourth proportional to 78.72, 118.16 and 55.86 is: 83.85

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.72 : 118.16 = 55.86 : x
  2. Step 2: Convert to fraction form
    78.72/118.16 = 55.86/x
  3. Step 3: Cross multiply
    78.72x = 118.16 × 55.86
  4. Step 4: Simplify right side
    78.72x = 6,600.42
  5. Step 5: Solve for x
    x = 6,600.42/78.72
  6. Step 6: Final answer
    x = 83.85

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.