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Finding the Fourth Proportional to 80.88, 111.68 and 56.40

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Solution

The fourth proportional to 80.88, 111.68 and 56.40 is: 77.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    80.88 : 111.68 = 56.40 : x
  2. Step 2: Convert to fraction form
    80.88/111.68 = 56.40/x
  3. Step 3: Cross multiply
    80.88x = 111.68 × 56.40
  4. Step 4: Simplify right side
    80.88x = 6,298.75
  5. Step 5: Solve for x
    x = 6,298.75/80.88
  6. Step 6: Final answer
    x = 77.88

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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.