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Finding the Fourth Proportional to 125.28, 172.85 and 81.68

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Solution

The fourth proportional to 125.28, 172.85 and 81.68 is: 112.68

Step by Step Solution

  1. Step 1: Write the proportion equation
    125.28 : 172.85 = 81.68 : x
  2. Step 2: Convert to fraction form
    125.28/172.85 = 81.68/x
  3. Step 3: Cross multiply
    125.28x = 172.85 × 81.68
  4. Step 4: Simplify right side
    125.28x = 14,117.12
  5. Step 5: Solve for x
    x = 14,117.12/125.28
  6. Step 6: Final answer
    x = 112.68

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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.