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Finding the Fourth Proportional to 99.85, 137.79 and 71.85

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Solution

The fourth proportional to 99.85, 137.79 and 71.85 is: 99.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.85 : 137.79 = 71.85 : x
  2. Step 2: Convert to fraction form
    99.85/137.79 = 71.85/x
  3. Step 3: Cross multiply
    99.85x = 137.79 × 71.85
  4. Step 4: Simplify right side
    99.85x = 9,900.21
  5. Step 5: Solve for x
    x = 9,900.21/99.85
  6. Step 6: Final answer
    x = 99.15

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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.