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Finding the Fourth Proportional to 753.78, 1,128.85 and 643.45

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Solution

The fourth proportional to 753.78, 1,128.85 and 643.45 is: 963.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    753.78 : 1,128.85 = 643.45 : x
  2. Step 2: Convert to fraction form
    753.78/1,128.85 = 643.45/x
  3. Step 3: Cross multiply
    753.78x = 1,128.85 × 643.45
  4. Step 4: Simplify right side
    753.78x = 726,358.53
  5. Step 5: Solve for x
    x = 726,358.53/753.78
  6. Step 6: Final answer
    x = 963.62

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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.