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Finding the Fourth Proportional to 103.92, 143.28 and 85.40

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Solution

The fourth proportional to 103.92, 143.28 and 85.40 is: 117.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    103.92 : 143.28 = 85.40 : x
  2. Step 2: Convert to fraction form
    103.92/143.28 = 85.40/x
  3. Step 3: Cross multiply
    103.92x = 143.28 × 85.40
  4. Step 4: Simplify right side
    103.92x = 12,236.11
  5. Step 5: Solve for x
    x = 12,236.11/103.92
  6. Step 6: Final answer
    x = 117.75

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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.