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Finding the Fourth Proportional to 640.78, 961.64 and 435.56

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Solution

The fourth proportional to 640.78, 961.64 and 435.56 is: 653.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    640.78 : 961.64 = 435.56 : x
  2. Step 2: Convert to fraction form
    640.78/961.64 = 435.56/x
  3. Step 3: Cross multiply
    640.78x = 961.64 × 435.56
  4. Step 4: Simplify right side
    640.78x = 418,851.92
  5. Step 5: Solve for x
    x = 418,851.92/640.78
  6. Step 6: Final answer
    x = 653.66

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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.