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Finding the Fourth Proportional to 102.90, 154.26 and 85.92

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Solution

The fourth proportional to 102.90, 154.26 and 85.92 is: 128.80

Step by Step Solution

  1. Step 1: Write the proportion equation
    102.90 : 154.26 = 85.92 : x
  2. Step 2: Convert to fraction form
    102.90/154.26 = 85.92/x
  3. Step 3: Cross multiply
    102.90x = 154.26 × 85.92
  4. Step 4: Simplify right side
    102.90x = 13,254.02
  5. Step 5: Solve for x
    x = 13,254.02/102.90
  6. Step 6: Final answer
    x = 128.80

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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.