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Finding the Fourth Proportional to 643.76, 965.64 and 427.76

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Solution

The fourth proportional to 643.76, 965.64 and 427.76 is: 641.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.76 : 965.64 = 427.76 : x
  2. Step 2: Convert to fraction form
    643.76/965.64 = 427.76/x
  3. Step 3: Cross multiply
    643.76x = 965.64 × 427.76
  4. Step 4: Simplify right side
    643.76x = 413,062.17
  5. Step 5: Solve for x
    x = 413,062.17/643.76
  6. Step 6: Final answer
    x = 641.64

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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.