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Finding the Fourth Proportional to 78.16, 107.92 and 61.84

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Solution

The fourth proportional to 78.16, 107.92 and 61.84 is: 85.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    78.16 : 107.92 = 61.84 : x
  2. Step 2: Convert to fraction form
    78.16/107.92 = 61.84/x
  3. Step 3: Cross multiply
    78.16x = 107.92 × 61.84
  4. Step 4: Simplify right side
    78.16x = 6,673.77
  5. Step 5: Solve for x
    x = 6,673.77/78.16
  6. Step 6: Final answer
    x = 85.39

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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.