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Finding the Fourth Proportional to 402.50, 603.76 and 128.78

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Solution

The fourth proportional to 402.50, 603.76 and 128.78 is: 193.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    402.50 : 603.76 = 128.78 : x
  2. Step 2: Convert to fraction form
    402.50/603.76 = 128.78/x
  3. Step 3: Cross multiply
    402.50x = 603.76 × 128.78
  4. Step 4: Simplify right side
    402.50x = 77,752.21
  5. Step 5: Solve for x
    x = 77,752.21/402.50
  6. Step 6: Final answer
    x = 193.17

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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.