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Finding the Fourth Proportional to 80.76, 120.90 and 56.30

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Solution

The fourth proportional to 80.76, 120.90 and 56.30 is: 84.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.76 : 120.90 = 56.30 : x
  2. Step 2: Convert to fraction form
    80.76/120.90 = 56.30/x
  3. Step 3: Cross multiply
    80.76x = 120.90 × 56.30
  4. Step 4: Simplify right side
    80.76x = 6,806.67
  5. Step 5: Solve for x
    x = 6,806.67/80.76
  6. Step 6: Final answer
    x = 84.28

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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.