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Finding the Fourth Proportional to 78.39, 117.38 and 54.09

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Solution

The fourth proportional to 78.39, 117.38 and 54.09 is: 80.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.39 : 117.38 = 54.09 : x
  2. Step 2: Convert to fraction form
    78.39/117.38 = 54.09/x
  3. Step 3: Cross multiply
    78.39x = 117.38 × 54.09
  4. Step 4: Simplify right side
    78.39x = 6,348.48
  5. Step 5: Solve for x
    x = 6,348.48/78.39
  6. Step 6: Final answer
    x = 80.99

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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.