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Finding the Fourth Proportional to 99.40, 149.12 and 85.84

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Solution

The fourth proportional to 99.40, 149.12 and 85.84 is: 128.78

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.40 : 149.12 = 85.84 : x
  2. Step 2: Convert to fraction form
    99.40/149.12 = 85.84/x
  3. Step 3: Cross multiply
    99.40x = 149.12 × 85.84
  4. Step 4: Simplify right side
    99.40x = 12,800.46
  5. Step 5: Solve for x
    x = 12,800.46/99.40
  6. Step 6: Final answer
    x = 128.78

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.