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Finding the Fourth Proportional to 99.24, 148.80 and 85.78

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Solution

The fourth proportional to 99.24, 148.80 and 85.78 is: 128.61

Step by Step Solution

  1. Step 1: Write the proportion equation
    99.24 : 148.80 = 85.78 : x
  2. Step 2: Convert to fraction form
    99.24/148.80 = 85.78/x
  3. Step 3: Cross multiply
    99.24x = 148.80 × 85.78
  4. Step 4: Simplify right side
    99.24x = 12,763.73
  5. Step 5: Solve for x
    x = 12,763.73/99.24
  6. Step 6: Final answer
    x = 128.61

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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.