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Finding the Fourth Proportional to 99.85, 137.73 and 78.07

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Solution

The fourth proportional to 99.85, 137.73 and 78.07 is: 107.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.85 : 137.73 = 78.07 : x
  2. Step 2: Convert to fraction form
    99.85/137.73 = 78.07/x
  3. Step 3: Cross multiply
    99.85x = 137.73 × 78.07
  4. Step 4: Simplify right side
    99.85x = 10,752.58
  5. Step 5: Solve for x
    x = 10,752.58/99.85
  6. Step 6: Final answer
    x = 107.69

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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.