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Finding the Fourth Proportional to 84.12, 116.57 and 78.72

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Solution

The fourth proportional to 84.12, 116.57 and 78.72 is: 109.08

Step by Step Solution

  1. Step 1: Write the proportion equation
    84.12 : 116.57 = 78.72 : x
  2. Step 2: Convert to fraction form
    84.12/116.57 = 78.72/x
  3. Step 3: Cross multiply
    84.12x = 116.57 × 78.72
  4. Step 4: Simplify right side
    84.12x = 9,176.00
  5. Step 5: Solve for x
    x = 9,176.00/84.12
  6. Step 6: Final answer
    x = 109.08

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Why These Related Problems?

These problems maintain the same ratio (1.39) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.