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Finding the Fourth Proportional to 78.20, 117.26 and 39.66

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Solution

The fourth proportional to 78.20, 117.26 and 39.66 is: 59.47

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.20 : 117.26 = 39.66 : x
  2. Step 2: Convert to fraction form
    78.20/117.26 = 39.66/x
  3. Step 3: Cross multiply
    78.20x = 117.26 × 39.66
  4. Step 4: Simplify right side
    78.20x = 4,650.26
  5. Step 5: Solve for x
    x = 4,650.26/78.20
  6. Step 6: Final answer
    x = 59.47

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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.