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Finding the Fourth Proportional to 99.20, 136.58 and 78.37

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Solution

The fourth proportional to 99.20, 136.58 and 78.37 is: 107.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.20 : 136.58 = 78.37 : x
  2. Step 2: Convert to fraction form
    99.20/136.58 = 78.37/x
  3. Step 3: Cross multiply
    99.20x = 136.58 × 78.37
  4. Step 4: Simplify right side
    99.20x = 10,703.04
  5. Step 5: Solve for x
    x = 10,703.04/99.20
  6. Step 6: Final answer
    x = 107.89

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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.