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Finding the Third Proportional to 420.75 and 643.13

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Solution

The third proportional to 420.75 and 643.13 is: 983.03

Step by Step Solution

  1. Step 1: Write the proportion equation
    420.75 : 643.13 = 643.13 : x
  2. Step 2: Convert to fraction form
    420.75/643.13 = 643.13/x
  3. Step 3: Cross multiply
    420.75x = 643.13 × 643.13
  4. Step 4: Simplify right side
    420.75x = 413,609.77
  5. Step 5: Solve for x
    x = 413,609.77/420.75
  6. Step 6: Final answer
    x = 983.03

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Why These Related Problems?

These problems maintain the same ratio (1.53) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.