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Finding the Third Proportional to 421.13 and 642.56

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Solution

The third proportional to 421.13 and 642.56 is: 980.44

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.13 : 642.56 = 642.56 : x
  2. Step 2: Convert to fraction form
    421.13/642.56 = 642.56/x
  3. Step 3: Cross multiply
    421.13x = 642.56 × 642.56
  4. Step 4: Simplify right side
    421.13x = 412,886.57
  5. Step 5: Solve for x
    x = 412,886.57/421.13
  6. Step 6: Final answer
    x = 980.44

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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.