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Finding the Fourth Proportional to 80.40, 120.60 and 56.40

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Solution

The fourth proportional to 80.40, 120.60 and 56.40 is: 84.60

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.40 : 120.60 = 56.40 : x
  2. Step 2: Convert to fraction form
    80.40/120.60 = 56.40/x
  3. Step 3: Cross multiply
    80.40x = 120.60 × 56.40
  4. Step 4: Simplify right side
    80.40x = 6,801.84
  5. Step 5: Solve for x
    x = 6,801.84/80.40
  6. Step 6: Final answer
    x = 84.60

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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.