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Finding the Fourth Proportional to 99.20, 136.89 and 57.75

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Solution

The fourth proportional to 99.20, 136.89 and 57.75 is: 79.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.20 : 136.89 = 57.75 : x
  2. Step 2: Convert to fraction form
    99.20/136.89 = 57.75/x
  3. Step 3: Cross multiply
    99.20x = 136.89 × 57.75
  4. Step 4: Simplify right side
    99.20x = 7,905.40
  5. Step 5: Solve for x
    x = 7,905.40/99.20
  6. Step 6: Final answer
    x = 79.70

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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.