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Finding the Fourth Proportional to 268.38, 402.64 and 85.78

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Solution

The fourth proportional to 268.38, 402.64 and 85.78 is: 128.69

Step by Step Solution

  1. Step 1: Write the proportion equation
    268.38 : 402.64 = 85.78 : x
  2. Step 2: Convert to fraction form
    268.38/402.64 = 85.78/x
  3. Step 3: Cross multiply
    268.38x = 402.64 × 85.78
  4. Step 4: Simplify right side
    268.38x = 34,538.46
  5. Step 5: Solve for x
    x = 34,538.46/268.38
  6. Step 6: Final answer
    x = 128.69

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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.