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Finding the Fourth Proportional to 78.18, 117.27 and 39.15

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Solution

The fourth proportional to 78.18, 117.27 and 39.15 is: 58.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.18 : 117.27 = 39.15 : x
  2. Step 2: Convert to fraction form
    78.18/117.27 = 39.15/x
  3. Step 3: Cross multiply
    78.18x = 117.27 × 39.15
  4. Step 4: Simplify right side
    78.18x = 4,590.73
  5. Step 5: Solve for x
    x = 4,590.73/78.18
  6. Step 6: Final answer
    x = 58.72

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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.